We're starting an Icewind Dale campaign with level 15'ish characters we've built up through 4 previous campaigns. The team is concerned that one player (pyromancer, Roy "Trogdor" Mustang the Burninator of Amestris) will be exceedingly overpowered, and the DM seems to be in favor of some overpowered features from unearthed arcana. The team thinks the pyromancer should branch out a bit for spells, but "Roy" insists on staying in-character, and that "anything should be able to burn". This is what the typical battle looks like:
Problems: Burninate all the Things
Fire in the Veins: At 6th level, you gain resistance to fire damage. In addition, spells you cast ignore resistance to fire damage.
Fiery Soul: At 18th level, you gain immunity to fire damage. In addition, any spell or effect you create ignores resistance to fire damage and treats immunity to fire damage as resistance to fire damage.
And from the Player's Handbook:
Elemental Adept - Fire. Prerequisite: The ability to cast at least one spell. When you gain this feat, choose one of the following damage types: acid, cold, fire, lightning, or thunder. Spells you cast ignore resistance to damage of the chosen type. In addition, when you roll damage for a spell you cast that deals damage of that type, you can treat any 1 on a damage die as a 2. You can select this feat multiple times. Each time you do so, you must choose a different damage type.
Roy is already wandering into the middle of a crowd of enemies, using wall of fire, and encircling enemies plus himself, and roasting all the enemies (ignoring enemy resistance on his attacks, and also having resistance on self damage against himself, so he's less likely to take damage), and uses font of magic to further skew this. The DM has already ruled that when Roy hits level 18, he is immune to his own self-damage, and against enemies:
- Treats immunity to fire as resistance to fire (Fiery Soul), and further treats that immunity-reduced-to-resistance as no resistance at all (i.e. allowing this to stack with Elemental Adept, largely due to another answer on this site, and this answer too).
- Can use Font of Magic to further boost this, and basically nuke an entire area while being in the middle of it, while taking no damage from his own spells.
- He has resistance to fire attacks against himself, and ignores resistance to fire by enemies. Pretty soon, he will be immune to his own attacks, and can ignore resistance and immunity to fire by enemies.
We had a vote to introduce some iron golems into the campaign, which appear to have the ability to absorb fire damage, even from Roy:
Fire Absorption. Whenever the golem is subjected to fire damage, it takes no damage and instead regains a number of hit points equal to the fire damage dealt.
However, the DM has ruled that the "spirit" (i.e. intent) of the stacking of Fiery Soul and Elemental Adept would also bypass the fire absorption (i.e. "If this fire can set fire and lightning elementals on fire, a golem would be just as vulnerable to the same damage").
Is there anything we can throw into the game, without changing the DM's rulings, that would prevent this one pyromancer min-max'er from dominating the battlefield? We're not trying to get them to leave, but the game is getting a bit boring with one person running into the middle of the battlefield and just nuking everything.