The comeback kid + leech combo should be nerfed.
Anyway, I can heal my whole party almost instantly by casting fireball on them, because they have very high elemental resistance to fire. Meteor shower is the best though, I can watch the enemy burn to ashes while my party heals while basking in the extreme heat. My entire party actually has 100+ percent resistance to every element, so even breathing in poison heals them too.

...That is much worse than leech, but nobody seems to care. Strange how that works.