When you multiclass, you sacrifice a level (or more) in order to gain the damage number of levels in a different class. The initial levels also tend to be the most intensive in features, which is probably why you lose the HP gain to balance it. You also lose levels (in the sense that you can no longer hit levels 20) and you may lose features (the later ones thatnare unreachable due to not gaining those levels in your main class). On the other hand, you obtain some pretty powerful features and strengths.

I know that multiclassing is often used for flavour. If you wanted to recreate Aragorn, you don't want a straight Ranger or a Fighter. However, in terms of mechanics and how strong the character would be, is it more advantageous to multiclass and suck up the sacrifices or to give it a miss and go pure?

I have a similar question about ASI v Feats, but not sure I want to spam the board! 

Quote from Linklite >>

If you wanted to recreate Aragorn, you don't want a straight Ranger or a Fighter.

No, you want a straight Paladin with an outdoorsy background. I'm not really kidding either. ;-)

The answer to your question is that it depends, as hashed out here and here, among other threads. It depends on how synergistic the multiclass is, and on how many levels your character will have by the time it gets retired, and on where you are in the build, etc. 

There’s no hard-and-fast answer. You give up depth for breadth. You get more tricks you can pull off, but won’t be as good at them as someone who didn’t multiclass. Whether or not it’s a good choice depends on whether it succeeds in what you are trying to do — and of course if you are having fun, that beats everything else. 
There was one consideration you left out, how high a level is the campaign going. If your character doesn’t really come together until you are a something 5/something 7, and the campaign will end at level 10, you never really get to be what you wanted.

And if you’re new, be careful with it. Multiclassing poorly is the best way to make an ineffective character.

If it’s something you’re considering, I’d say give us the specific idea, and folks will be better able to answer the question. 

And as far as asi vs feats, it will similarly be situation-dependent which is better. But again, what’s most important is that you have fun, not how much damage per round you can do.

Given that the average game rarely goes past level 12 not reaching level 20 (or the capstone features) is hardly that big of detriment.
And given the nature of sub-classes, skills, backgrounds, and feats; IMO, outside of a couple of unique mechanically based ones most concepts can be obtained as single classes and through judicious selection of the aforementioned classes, background, skills, feats, etc...

Quote from pangurjan >>

Quote from Linklite >>

If you wanted to recreate Aragorn, you don't want a straight Ranger or a Fighter.

No, you want a straight Paladin with an outdoorsy background. I'm not really kidding either. ;-)

 This.  Aragorn in DND terms is a Fighter or Paladin with Outsider background, and appropriate skill and feat selection.  I’d say a fighter.

Hes also incredibly experienced.  Aragorn is 87 years old at the War of the Ring.  He rode to war decades earlier with Thengel, Theoden’s father. He’s surely an epic level character by LotR.

The title Ranger and the class Ranger aren’t the same thing…  

Quote from Linklite>>

…The initial levels also tend to be the most intensive in features, which is probably why you lose the HP gain to balance it.

I wanted to ask about this. What do you mean “lose the HP gain to balance it?” Multiclassing does not preclude gaining HP, you still get the hit die and hit points for the level(s) in your new multiclass. If you have a 10th level Fighter and add a level of Ranger then you have 11d10 hit dice. If you are a 10th level Rogue and take a level in Wizard you would have 10d8+1d6 hit dice. If you are a 10th level Sorcerer and gain a level of Paladin you would have 10d6+1d10 hit dice.

The rule is that you gain hit dice plus constitution modifier per class level after first.  To me, that means that if I'm a Wizard at l9 about to go l10 with say a constitution of 14, I can either have another Wizard level and gain 2*9 plus hit dice, or go, say, Sorceror for 2*1 plus hit dice. Your hit dice woukd be thensame (so long as you aren't on d10s and then MC as a class with d6s or d8s), but max HP would be affected.

Sorry, but I don't understand the what you are saying here.  Can you explain it again?

Quote from Linklite >>

The rule is that you gain hit dice plus constitution modifier per class level after first.  To me, that means that if I'm a Wizard at l9 about to go l10 with say a constitution of 14, I can either have another Wizard level and gain 2*9 plus hit dice, or go, say, Sorceror for 2*1 plus hit dice. Your hit dice woukd be thensame (so long as you aren't on d10s and then MC as a class with d6s or d8s), but max HP would be affected.

That is not how it works. The constitution modifier applies to each individual level, not just to your initial class's level. If your con mod is +2, at level ten regardless of class or multicleass, you get 18 HP (2 mod * 9 levels) from your con mod. From Basic Rules:

"
Class Features and Hit Dice

When your character gains a level, his or her class often grants additional features, as detailed in the class description. Some of these features allow you to increase your ability scores, either increasing two scores by 1 each or increasing one score by 2. You can’t increase an ability score above 20. In addition, every character's proficiency bonus increases at certain levels.

Each time you gain a level, you gain 1 additional Hit Die. Roll that Hit Die, add your Constitution modifier to the roll, and add the total (minimum of 1) to your hit point maximum. Alternatively, you can use the fixed value shown in your class entry, which is the average result of the die roll (rounded up).

When your Constitution modifier increases by 1, your hit point maximum increases by 1 for each level you have attained. For example, if your 7th-level fighter has a Constitution score of 17, when he reaches 8th level, he increases his Constitution score from 17 to 18, thus increasing his Constitution modifier from +3 to +4. His hit point maximum then increases by 8.
"

Quote from Linklite >>

The rule is that you gain hit dice plus constitution modifier per class level after first.  To me, that means that if I'm a Wizard at l9 about to go l10 with say a constitution of 14, I can either have another Wizard level and gain 2*9 plus hit dice, or go, say, Sorceror for 2*1 plus hit dice. Your hit dice woukd be thensame (so long as you aren't on d10s and then MC as a class with d6s or d8s), but max HP would be affected.

 From the Basic Rules (emphasis mine):

"You gain the hit points from your new class as described for levels after 1st. You gain the 1st-level hit points for a class only when you are a 1st-level character.

You add together the Hit Dice granted by all your classes to form your pool of Hit Dice. If the Hit Dice are the same die type, you can simply pool them together. For example, both the fighter and the paladin have a d10, so if you are a paladin 5/fighter 5, you have ten d10 Hit Dice. If your classes give you Hit Dice of different types, keep track of them separately. If you are a paladin 5/cleric 5, for example, you have five d10 Hit Dice and five d8 Hit Dice."

Essentially, you gain hit points the same way regardless of class and/or multiclass - maximum (based on your hit die and your Con) at level 1, then a rolled die's worth + Con every new level (exceptions due to a feat or item might apply, but this is how it otherwise works for any and all characters). All that multiclassing (potentially) changes is the hit die size for the level you take next. The way it's worded is a bit silly due to the Con bonus being retroactive (if your Con mod changes, so do your hit points for all levels), but it's pretty simple in practice. 

Wiz 1 with Con 13: 6+1=7.
Wiz 2 with Con 13: 6+1d6(let's say a roll of 5)+2x1(Con mod once for your first level and then once more for every level after the first)=13
Wiz 3 with Con 13: 6+2d6(let's say you roll a 3 at this level, to add to the 5 from the previous one)+3x1=17

Now you multiclass into Artificer at lvl 4:
Wiz 3/Art 1 with Con 13: 6+2d6(rolled to be 8)+1d8(let's say 4)+4x1(still Con mod once for your first level and then once more for every level after the first)=22
Wiz 3/Art 2 with Con 13: 6+2d6(8)+2d8(4+let's say 7)+5x1=30

Back to Wizard, and you use your ASI to even out your Con to 14, for a +2 modifier:
Wiz 4/Art2 with Con 14: 6+3d6(8+let's say 3)+2d8(11)+6x2(new Con mod once for your first level and then once more for every level after the first)=40

And so on. 

Wasn't aragorn really good at tracking/outdoorsey stuff etc? That would suggest at least some ranger to me. I'm a bit confused by the paladin bit. 

I suppose he does do the healing thing in return of the king, is that where the paladin bit's coming from? I"m not sure I'd give him paladin levels unless there's more to it than that. 

Aragorn is a paladin because of his character. He's defined by his inner strength, his resolve and his leadership. That screams paladin to me. The healing bit is apt, but magic being used is extremely rare in LotR - he'd be a paladin to me without that too. Everything else is just the right proficiencies (background helps) and ability modifiers.

Quote from Nyr_Ventus >>

Wasn't aragorn really good at tracking/outdoorsey stuff etc? That would suggest at least some ranger to me. I'm a bit confused by the paladin bit. 

I suppose he does do the healing thing in return of the king, is that where the paladin bit's coming from? I"m not sure I'd give him paladin levels unless there's more to it than that. 

 The bolded part can be obtained through background or feat choices no need for a specific class to gain this.

Quote from pangurjan >>

Aragorn is a paladin because of his character. He's defined by his inner strength, his resolve and his leadership. That screams paladin to me. The healing bit is apt, but magic being used is extremely rare in LotR - he'd be a paladin to me without that too. Everything else is just the right proficiencies (background helps) and ability modifiers.

 I had never thought about it that way until now. He is a great leader and very inspiring, hence bonuses to saving throws. Other spells and effects don't necessarily have to have flashy special effects, they just have to work - toughness in battle, aiding an ally, striking hard or avoiding/absorbing damage. Interesting.

Linklite,

It seems you had a slight misunderstanding. As was already pointed out in the following two helpful posts, you don’t sacrifice HP the way you thought:

Quote from XXXGammaRay >>

Quote from Linklite >>

The rule is that you gain hit dice plus constitution modifier per class level after first.  To me, that means that if I'm a Wizard at l9 about to go l10 with say a constitution of 14, I can either have another Wizard level and gain 2*9 plus hit dice, or go, say, Sorceror for 2*1 plus hit dice. Your hit dice woukd be thensame (so long as you aren't on d10s and then MC as a class with d6s or d8s), but max HP would be affected.

That is not how it works. The constitution modifier applies to each individual level, not just to your initial class's level. If your con mod is +2, at level ten regardless of class or multicleass, you get 18 HP (2 mod * 9 levels) from your con mod. From Basic Rules:

"
Class Features and Hit Dice

When your character gains a level, his or her class often grants additional features, as detailed in the class description. Some of these features allow you to increase your ability scores, either increasing two scores by 1 each or increasing one score by 2. You can’t increase an ability score above 20. In addition, every character's proficiency bonus increases at certain levels.

Each time you gain a level, you gain 1 additional Hit Die. Roll that Hit Die, add your Constitution modifier to the roll, and add the total (minimum of 1) to your hit point maximum. Alternatively, you can use the fixed value shown in your class entry, which is the average result of the die roll (rounded up).

When your Constitution modifier increases by 1, your hit point maximum increases by 1 for each level you have attained. For example, if your 7th-level fighter has a Constitution score of 17, when he reaches 8th level, he increases his Constitution score from 17 to 18, thus increasing his Constitution modifier from +3 to +4. His hit point maximum then increases by 8.
"

Quote from pangurjan >>

Quote from Linklite >>

The rule is that you gain hit dice plus constitution modifier per class level after first.  To me, that means that if I'm a Wizard at l9 about to go l10 with say a constitution of 14, I can either have another Wizard level and gain 2*9 plus hit dice, or go, say, Sorceror for 2*1 plus hit dice. Your hit dice woukd be thensame (so long as you aren't on d10s and then MC as a class with d6s or d8s), but max HP would be affected.

 From the Basic Rules (emphasis mine):

"You gain the hit points from your new class as described for levels after 1st. You gain the 1st-level hit points for a class only when you are a 1st-level character.

You add together the Hit Dice granted by all your classes to form your pool of Hit Dice. If the Hit Dice are the same die type, you can simply pool them together. For example, both the fighter and the paladin have a d10, so if you are a paladin 5/fighter 5, you have ten d10 Hit Dice. If your classes give you Hit Dice of different types, keep track of them separately. If you are a paladin 5/cleric 5, for example, you have five d10 Hit Dice and five d8 Hit Dice."

Essentially, you gain hit points the same way regardless of class and/or multiclass - maximum (based on your hit die and your Con) at level 1, then a rolled die's worth + Con every new level (exceptions due to a feat or item might apply, but this is how it otherwise works for any and all characters). All that multiclassing (potentially) changes is the hit die size for the level you take next. The way it's worded is a bit silly due to the Con bonus being retroactive (if your Con mod changes, so do your hit points for all levels), but it's pretty simple in practice. 

Wiz 1 with Con 13: 6+1=7.
Wiz 2 with Con 13: 6+1d6(let's say a roll of 5)+2x1(Con mod once for your first level and then once more for every level after the first)=13
Wiz 3 with Con 13: 6+2d6(let's say you roll a 3 at this level, to add to the 5 from the previous one)+3x1=17

Now you multiclass into Artificer at lvl 4:
Wiz 3/Art 1 with Con 13: 6+2d6(rolled to be 8)+1d8(let's say 4)+4x1(still Con mod once for your first level and then once more for every level after the first)=22
Wiz 3/Art 2 with Con 13: 6+2d6(8)+2d8(4+let's say 7)+5x1=30

Back to Wizard, and you use your ASI to even out your Con to 14, for a +2 modifier:
Wiz 4/Art2 with Con 14: 6+3d6(8+let's say 3)+2d8(11)+6x2(new Con mod once for your first level and then once more for every level after the first)=40

And so on. 

 
They aren’t steering you wrong, so don’t cheat yourself. K?

Aragorn's healing was mostly herbalism, medicine and perhaps goodberries. He does have some Paladin qualities to him but as mentioned not really anything that fits with a vow in 5E terms. "I want to be the king" is more of a goal than a vow. Nor does he smite stuff, fight demons or anything other typical for paladins. Custom lineage Fighter/Ranger works best. Especially considering he has orcs as a favoured enemy. Fun fact, Aragorn's parents (his dad at least) was killed by orcs, making Aragorn one of the original "my parents were killed by orcs, and now I'm out for revenge"-ers. :D

@OP. As mentioned, there are no easy answers. Some multiclass combos are better than others, sometimes you do it just for fun or because it fits really well. I know of a dwarf vengeance paladin that multiclassed partly because the idea of the capstone ability (a dwarf sprouting wings and flying, but a bit slow) just seemed rather silly and out of place. :P But as been mentioned, you don't really lose HP in the way you describe. Your level 10 Wizard would have the exact amount of HP as your wizard9/Sorcerer 1 since wizards and sorcerers have the same hit die.

It does make more sense, but I still hold that the wording (per Wizarding level) is very poor. They should have just made a separate statement, like "if your constitution modifier increases, multiply the invrease by your total level and then add that to your Max HP". Or a better way. It's misleading.

Thanks for correcting me. 

Quote from Damian_Magecraft >>

Quote from Nyr_Ventus >>

Wasn't aragorn really good at tracking/outdoorsey stuff etc? That would suggest at least some ranger to me. I'm a bit confused by the paladin bit. 

I suppose he does do the healing thing in return of the king, is that where the paladin bit's coming from? I"m not sure I'd give him paladin levels unless there's more to it than that. 

 The bolded part can be obtained through background or feat choices no need for a specific class to gain this.

I mean, that cuts both ways

Quote from Nyr_Ventus >>

Wasn't aragorn really good at tracking/outdoorsey stuff etc? That would suggest at least some ranger to me. I'm a bit confused by the paladin bit. 

 Aragorn and his forbears did swear to protect the North as Rangers, in penance  for failing to protect it as kings.

I want to be the king" is more of a goal than a vow.

He didn’t want to be king, and he and his forbears forswore the crown they thought they had lost the right to wear.

They were about protecting the people of the North, and were wood-wise, but not so much about protecting the woods themselves.

In 5e terms there is nothing Ranger-ey about the Rangers if the North, especially given the setting’s low manna magic.  Every magic using character was a supernatural being who had existed for thousands of years by the time of the story.

If we're accounting for LOTR being a low magic setting, especially in terms of humans, I'd probably just make him a fighter. If we take things relative, I might put him in with some ranger because of, as stated, being wood wise. Great at tracking etc, maybe with goblins/orcs for favored enemy selections etc. It's not a perfect fit but seems to fit pretty well IMO. Paladin feels like a stretch to me, but it's also an apples to oranges comparison as well between middle earth and the magic heavy 5E in general, I can see where people are coming from with paladin but just doesn't quite feel right to me either. I guess it may also depend on if you're looking at him at the start or end of the trilogy somewhat as well. 

I'll also admit I only read the books once back in high school and am more famliar with the movies, which have also been several years sine I watched, so maybe I have some things mixed up in my head as well.