Regeneration => pain absorption. Essence: a kind of bloodlust (which in Heroes 3 is fire), but with a different effect. Instead of increasing damage, it gradually absorbs it, resulting in a state close to berserk.
Phantom => flaming phantom. Essence: an unstable copy of a unit that can move and deal damage, but is relatively easily destroyed.
Blessing => righteous wrath (since there is no such skill anymore, as I understand).
Scatter => sleep. Essence: using water and cold to make an enemy unit incapacitated.
Slow => slow. I don't see a problem here.
And so on.