Mythics aside, don’t forget about Krystenax (enchant on Purple, DPS+summons, Stoneskin) or Arcanus (Dispel, Magic gain and self-Enchant). Bone Golem is also usable as a frontline tank (and for the randomness of Death Marks).
And since Raid Boss and Underspire have the same requirements, don’t forget Lord Ehrondil (or the newer Godslayer) if you need extra help on the boss teams specifically.