So i have been making homebrew magic items to hopefully end up making a patreon and my thing is figuring out the damage. I always have trouble on figuring out what the damage should be for a magic item, not knowing if its too much or too little. 

Does it depend on rarity and how many other effects it has? I never know whats a good average of damage if its based on rarity.

Damage for what?

Is it a magic weapon? The damage is based on the weapon and the rarity is based on what else it does.

Is it a magic something else?

You’re gonna hafta give us more info.

My fault haha

So starting off simple, I made a shortsword that has a scale of a dragon embedded into it. It deals 1d6 (because shortsword) and an additional 1d6 but the type of damage the extra damage does is based on the scale it has (red=fire damage or bronze= lightning damage). I have it set as rare. Not sure if that is in the right category or if it should be brought down to uncommon. 

I also have a gem that can manipulate space. So i have it use charges and you can expend 1 charge to teleport X amount of feet or expend more charges to teleport to a different plane. I have that has legendary. Not sure if that is also categorized right.

For stuff like that I usually check for comps (comparisons) and go from there. For example, a flame tongue Shortsword would be Rare and add 2d6 fire damage on a hit. Now, it also produces light, but by the same token fire is, like, the most resisted damage type in the game. Yours doesn’t shed light, but it might have different damage types, so it’s about a push, so I’d probably go with Uncommon.

As for the gem, that gets a little trickier. How far is “X feet” for example? Are we talkin’ misty step ranges, are we talkin’ teleport ranges or something in between here? And what are the stipulations if any? That makes a bii—iig difference. Does it allow you to cast a spell to teleport, or can you just use it as an action or something? That also makes a big difference since an item that can just teleport someone without casting a spell gets around all the Spellcasting restrictions, like, for example, a Barbarian could use it while raging which could be a hugemongous advantage. Does it take an action to use, or a bonus action, or what? Those also make a difference.  See what I mean?

My mindset was on the story side of things for the sword like how often do you encounter a dragon to get a scale from it or in general how to often do you come across a dragon scale just laying around. That's why I put rare.

I was just generalizing for the gem but pretty much yeah. Its a bonus action to spend 1 charge to cast mist step, action to spend 3 to cast teleport, and action to spend 5 to cast gate. You do have to attune to it. The idea here is the more power you use, the farther you go, essentially going to another plane. 

I do see what you mean in terms of balancing like your barbarian example. That could be troublesome lol.

Gate is a 9th-level spell, so that would be Legendary. There’s a chart for that stuff in the DMG: (https://www.dndbeyond.com/sources/dmg/dungeon-masters-workshop#CreatingaMagicItem). I would say yes, it requires Attunement.

The flame tongue is a bit overtuned compared to other weapons IMO and I wouldn't use it as a basis of comparison. 1d6 on every hit is quite good in the right hands and probably should be rare, especially if you're using damage types that are less often resisted than fire. This sounds a lot like the (rare) dragontooth dagger, which adds 1d6 acid and has a +1 to hit and damage. I'd probably model after that.

Quote from scatterbraind >>

The flame tongue is a bit overtuned compared to other weapons IMO and I wouldn't use it as a basis of comparison. 1d6 on every hit is quite good in the right hands and probably should be rare, especially if you're using damage types that are less often resisted than fire. This sounds a lot like the (rare) dragontooth dagger, which adds 1d6 acid and has a +1 to hit and damage. I'd probably model after that.

That dagger would probably only be uncommon if it didn’t have the +1 bonus though. Don’tcha think?

Talking more about it, which btw thank you for the insight and clarity, i struggle in how much extra damage to give to a weapon before its considered to strong. I saw that they have the static numbers to add based on rarity but what about if i add dice damage? 

If I changed the bonus damage on my shortsword to a 2d6 instead, I can assume that it would be to strong since there is no requirements to use the bonus, it just happens. Am I thinking about that right? 

Quote from Dbacon >>

Talking more about it, which btw thank you for the insight and clarity, i struggle in how much extra damage to give to a weapon before its considered to strong. I saw that they have the static numbers to add based on rarity but what about if i add dice damage? 

If I changed the bonus damage on my shortsword to a 2d6 instead, I can assume that it would be to strong since there is no requirements to use the bonus, it just happens. Am I thinking about that right? 

 
Then it would definitely be Rare if not Very Rare. One of the limitations on the flame tongue is that it requires a command word to activate. That means it’s hard to be stealthy with it because you have to say something out loud and then it lights up like Gimbals front window at Christmas time, but it also means that you cannot activate it at all if you are in a zone of magical silence. Flame tongue weapons are Rare and do an additional 2d6 damage, and on top of the fact that it’s the commonly resisted fire damage type, it has those other features that mitigate its power level, and even with all of that going on scatterbraind still says it’s overtuned for a Rare item. (And scatterbraind is probably right about that.)

As for the comparison between a static bonus compared to a die, the spells magic weapon and elemental weapon can provide a comp for you to consider. Magic weapon is a 2nd-level spell that grants a simple +1 to both attack and damage rolls when cast at that level. Elemental weapon is a (underpowered) 3rd-level spell that grants a +1 bonus to attack rolls but a 1d4 bonus to damage rolls at that level. I know that’s not a direct comp or anything, but it’s the closest comp I know of. Anyway, since both of those spells are in the same spell level range of 2nd—3rd-level spells, if you made a magic item that allowed you to cast either spell at its lowest level for a charge, it would be an Uncommon magic item. A simple +1 weapon is also Uncommon. So a weapon that has a +1 to attack rolls and a +1d4 to damage rolls should theoretically also come in as a top-tier Uncommon item, or a bottom-tier Rare item (remember, not all magic items of the same rarity have the same power level). So, theoretically, a weapon that only has a bonus of +1d6 to damage rolls should also fall in as either a top-tier Uncommon item or a bottom-tier Rare. As a bottom-tier Rare it’s unimpressive, as a top-tier Uncommon it’s baller. I’d rather make a baller item than a lackluster one. That’s my logic at any rate.