I have an idea for a Hill Dwarf, an honest to goodness tank that is mostly Monk.  I wanted to see if you all thought it was a decent idea.

It's predominantly a Way of Mercy Monk (14 levels total) but starts off with 3 levels of Ancestral Guardian Barbarian (6 total if it ever made it to 20).

Barb side provides huge boosts to teams defense/resists with the Guardians and rage giving personal resistances that are very nice.

Immune to Poison/Disease.

Can kill off Charmed/Frightened.

Can throw poison effect and stuns to go with the extra damage/turn and heals if you or team are running low.

Proficiency thrown on to saving throws.

AC can be in the low 20s once you start throwing on a couple forms of protection (Bracers, rings and whatnot). Can even go to a more turtle mode with a shield and get that up to like mid 20s (at the cost of a lot of damage potential).

Plus I love the idea of a dwarf running around at 60ft a turn. :)

Is this a workable idea or am I missing some crucial point of rules that would destroy the whole thing?

Well, it sounds like a really fun idea, but wearing a shield disables the bracers and trashes a bunch of your stats, so I'd definitely go shieldless and wear a cloak of protection instead.

Good call. I pretty much doffed that shield idea.

Was considering using Rapier and picking up defensive duelist so I'd have a normal reaction in combat to pop my AC up by my proficiency when baddie attacks me.  Would cost me two Con to do so.  Which means starting AC of one less and minus like 20 HP overall.  Allies still get the resistance to damage type and baddie gets disadvantage if they attack allies.  I think that's a good way to go.

I'd still have flurry of blows to do one  heal and one harm all for 1 ki point. 

Assuming all hit that should be 4d8 +15 or 3d8 +11 and  a heal of 1d8 +3 to keep me topped off.  This is without including any bonuses from magic weapon just to keep it simple. Not great damage but not terrible considering all the Tank-ability.

Still, the Monk Tank idea is great, and I'm definitely going to consider beefing my monk up, as he's the lowest hp in my party :)

The Hill Dwarf is, imo, a natural for this build but I'm seriously considering a Forest Gnome for the advantage on saving throws against magic and the pure comedy of the tank being a gnome.

Oh, another thing: this might require too many levels, but at lvl.17, Way of the Astral Self monks get a +2 AC bonus whenever their astral self is summoned (which costs 2 Ki every 10 minutes in-game) also, the Astral Self works great with a barbarian, and if you spend one attack to attack with the Astral Arms, you get THREE extra Astral Arm attacks as a bonus action.

So with the Monk's unarmored Defence giving +1 AC, plus another one for every DEX modifier  you have, the Cloak of Protection plus bracers giving you another +3, and the Armor of the Spirit from the astral self stacking another +2, that's +6 AC+DEX mod. from just being Lvl. 17 and using 2 attunement slots. Since monks are heavy on DEX, you can easily get up to 8, 9, or even 10 extra AC out of this!

Just another tip to potentially boost your AC by another 2, hope this helps :)

Monks AC's I've found really aren't that bad overall. AT least comparable to other skirmishers and with more ways to increase it than expected since they don't have to focus on finding the right kind of armors and such. So while the other martials for the most part are going after the armor and weapons in the horde. We can more be negotiating with the mage or the druid or the sorcerer about who gets which accessories and they can really help the monks AC.  The Hardest part about it tends to be how much it relies on our stats.  Even more than the barbarians does really because the barbarian has other defensive characteristics to their kit.

If one focuses on their stats and gets them maxed. Monks are fully capable of getting AC's as high as 26 or 27 just like the plate wearers in full +3 magicals.  Though 23 to 24 is perhaps more common.  And a 20 is still quite reachable if you can't quite max out those two stats.  That being said. the +2 from Astral Monk at those highest levels is still pretty nice and worth stacking on if your going to go Astral Monk.

My big suggestion for monks to round things out is to try and get your hands on things like the Amulet of Health if you can.  That 19 Con can be a nice boost to that important third stat and help a lot on all monks but most particularly if your looking to do some of the tanking.

I love tank monks!

My personal favourite tank-trait would be something that can brutally discourage people from trying to run, which Stunning Strike can be saved for. 

 Next, let’s think of Feats:

Dwarven Fortitude - even if they crush you with some bad rounds, a dodge round and healing will make you very resilient.

Crusher - any critical hit you make gives you a potent bonus on your further attacks.  This also means your opp attacks will be more likely to hit too, so spread it around. 

Fighting Initiate / Interception - When you’re forced to defend at close range, wield a staff and literally absorb damage that your allies would normally take.

Telekinetic (Wisdom) - with this and Crusher, you’ll be a master of pushing and pulling enemies (or allies) around the room.  And you can Push/Pull while action Dodging too. 

Pushing and pulling targets around with a monk is far simpler than taking a feat for it. Specially when you've got other feats lined up to take as well.  Some subclasses of monk have fairly good powers for pushing or pulling people around.  Open hand being good for pushing and knocking prone and it's easy to do with no real cost to the character. And surprisingly 4 Elements with just two Elemental powers can Push, Pull, Knock Prone and do damage while doing all three Though it does cost 2 ki each time you do it which can be somewhat expensive at lower levels.  These are just two examples from the PHB.

Quote from Wes_B >>

Oh, another thing: this might require too many levels, but at lvl.17, Way of the Astral Self monks get a +2 AC bonus whenever their astral self is summoned (which costs 2 Ki every 10 minutes in-game) also, the Astral Self works great with a barbarian, and if you spend one attack to attack with the Astral Arms, you get THREE extra Astral Arm attacks as a bonus action.

So with the Monk's unarmored Defence giving +1 AC, plus another one for every DEX modifier  you have, the Cloak of Protection plus bracers giving you another +3, and the Armor of the Spirit from the astral self stacking another +2, that's +6 AC+DEX mod. from just being Lvl. 17 and using 2 attunement slots. Since monks are heavy on DEX, you can easily get up to 8, 9, or even 10 extra AC out of this!

Just another tip to potentially boost your AC by another 2, hope this helps :)

 Ah yes, and if you manage to get this far: The robe of the Archmagi for your third attunement slot for another +2 AC

Just to let you guys know the way I'm putting this guy together:

Classes: Ancestral Guardian Barb 6 and Way of Mercy Monk 14.

I think I've decided on the Forest Gnome (see saving throws). Speed of 60. HP of 215. 

Saving throws are all either +8 or +11 with advantages on DEX against effects that you can see while not blinded, deafened, or incapacitated, on INT against Magic, on WIS against Magic, on CHA against Magic. Also STR with rage up.

D of 20. Defensive Dualist for adding Proficiency to melee attacks. If a huge fight can throw on a shield but then only two attacks (but flurry of blows still available to heal me or others). Total if needed going as high as 30. Shield would be rarely, if ever, actually used but maybe in that level 20 fight or something.

Resist to Bludgeon, Pierce, Slash with Rage. Immune to Disease, Poison. Can end Charmed or Frightened on myself for an action.

Ancestral Guardians give disadvantage to attacks against others for my target. If it still hits em, they get resist to that damage type. Also I can choose to get rid of 2d6 of the damage delivered.

Physicians touch can end blinded, deafened, paralyzed, poisoned, or stunned. on anyone on team.

Potential to stun or poison baddies.

Damage is actually not what I'm going after here. Averaging something like 5d8 +17 per round assuming not healing and all hit (somewhere near 40).

I went out of my way to not give myself any really uber pieces of equipment so it might be more of a fair representation of what he can do.

To me, this looks like a decent Tank... or maybe a Tankfender if you remember City of Heroes.

Could potentially give up as much as 3 levels of the Barb for an extra ASI or the resurrection power but would have to give up a rage slot (10 ft of speed and the ability to negate some damage to team). Not sure about this yet as 3 rages per long rest sounds a little sparse. Thoughts on that or anything else really?