Spirit of Rage exploit **minor spoilers

[Keneth]

You're telling me, I overupgraded my soul drain and it ended up costing me 70 rage per use, was waiting for that last rage reduction upgrade all the way until lvl30 but it never came. <_< Luckily I had +50% rage from the baby and +50% rage from Pain Skull (which was 2 enemies short of being upgraded at the end of the game by the way, waste of bloody artifact slot) so getting enough rage to cast it didn't prove that much of a problem. Black hole is useless though.