I've got a level 20 battle royale coming up. We could have any 3 magical items with DM approval.
Standard Array, Ive got:
8 STR, 14 DEX, 16 CON, 13 INT, 10 WIS, 20 CHA
I have War caster and Tough feats. 202 HP. 20 AC, 25 with shield.
I'm a level 20 Yuan Ti Pureblood Dragon Sorcerer. The DM approved my 3 items:
Green Dragon Mask, Rod of Absorption(9 levels stored, 16 used) and a Diamond spell gem with Shapechange cast into it.
I have advantage on saving throws against spells and magical effects and since I'm immune to poison,the green dragon mask lets me heal 1/2 any poison damage I take. It also allows me to add my CHA to my AC and gives me blindsight to 30th feet in addition to giving me 1 legendary resistance.
When I Shapechange, I'm choosing Ancient White Dragon first since it has the higher HP. First question, would the mask adjust size to fit the new forms if I choose to keep it on instead of merging it? Second question, after I use my 3 Legendary Resistances, if I change into an ancient brass dragon, would I gain their legendary resistances as well?
Yes it's OP(even if I don't get the LR of the new creatures) but keep in mind everyone else gets to build any way they want as well.
My level 9 spell is wish which I plan to use to completely heal my Ancient White Dragon form if I'm able before it drops to 0 HP. We allow any of the suggested uses of Wish without suffering the negative effects.
Any other suggestions or weaknesses I may have overlooked?
If you are immune to poison, why do you need to heal 1/2 of any poison damage you take?
"Damage Absorption. You have damage resistance to poison. If you already have damage resistance to poison from another source, you gain immunity to poison damage. If you already have immunity to poison damage from another source, you regain hit points equal to half of any poison damage you are dealt."
Even though they don't take damage, they still heal for what the damage would be.
The mask wouldnt change shape unless the item states it changes shape to match the form or your DM lets all items instantly reshape to fit the wearer. (do druids in your campaign still wear magical dragonhide when they are gazelles?)
Shapechange might not be allowed to benefit from legendary resistance at all, but if it does and you use it then reshape to the same or another form with legendary resistance? Again your DM will probably have to say that you dont get it, or you will switch back and forth forever refreshing it (probably not intended, and again not intended for LR to be accessible)
Carry wyvern poison vials in easily breakable clay strapped all over you, every time you are hit, heal x-number of vials worth of poison. This is already ludicrous enough, why not give yourself ablative armour?
A little update, someone asked for an artifact and so everyone was offered an artifact in place of one of their magic items. I convinced the DM that the Mask of the Dragon Queen should be considered an artifact and I've got it now.
According to Jeremy Crawford, legendary resistance is not a legendary action allowing you to gain LR with shapechange. DM is ruling that I only get 3 LR from shapechange. This is in addition to the 5 I get from the mask.
I won't be able to heal my dragon form with wish without suffering for it so I'm going to wish to cast simulacrum instead.
Now to the terrifying part that I had been overlooking... I've been focusing on flying and completely forgot about the ancient white dragon's 40 ft burrowing speed.
The individual masks reshape to fit the wearer attuned to it. The combined mask doesn't state it explicitly but the DM is allowing it.
Shapechange allows me to keep racial features so I'll heal with poison or cold damage. After spending 1 sorcery point with a fire spell, I'll be immune to fire. Only have resistance to lightning and acid.
With artifacts in play I'm pretty sure I'll be up against things such as the wand of orcus, the ring of winter, wyrmskull throne, eye and hand of vecna, orrery of the wanderer and other such items in addition to whelm, wave, etc.
I know one character is a totem barbarian with resistance to psychic from his race. I also know he's the one that asked for the artifact.
I've got a huge edge over the casters since I can just cancel really nasty spells with the the rod of absorption and they dont have access to subtle spell but I think the barbarian might be rough. I have to figure I'll only be laying down 1/4 damage on a lot of spells against him.
Hopefully my mass suggestion and scatter spells are helpful and I don't have to burn too many sorcery points on giving him disadvantage on suggestion if he isn't affected by mass suggestion.
I had the evil thought of trying to bury some of them alive.
We'll also have to contend with the arena. It gets a turn in combat and is going to be just as deadly as any of us.
It's also a pocket dimension of some sort and we were pulled there against our will. Summoning, planar travel, banishment and the like won't function.
Beware if the Barbarian has a starscape two handed sword, he might be starting with 200 to 400 temporary hitpoints on top of his hitpoints.
Check whether this summoning ban applies to familiars / find steeds / planar bindings. If it doesnt apply to planar bound entities that enter with you then a wizard or cleric might be bringing an elemental / fey payroll of workers with them. Also check if Demiplane is allowed, if not, starting with those or other allies in a demiplane, then opening it when the arena fight begins will grant the contestant an advantage.
Be on the look out for a flying ship with zombie crew, loaded down with siege weapons. Try not to get rammed.
If the arena itself is deadly and sapient, dont burrow. Your asking for trouble when your wrapping yourself in it.
It would be worth checking the artifacts dont include the orb of dragonkind, I havent seen them return in 5th but if they are present, you turning into a dragon is signing your death warrant.
If the way finders guide is being allowed beware of someone using rings of shared suffering on a regenerator (if they still share healing)
Good luck, it seems this fight will come down to who is the most devious.