| They have resistances. Vitality Damage is resisted less often than normal damage, but some creatures are (almost) immune to it, like undead. Bosses also have increased resistance to it.
Onslaught also raises Piercing damage, since it raises total damage, which leads to great amounts of damage.
Once again: look at the synergies of Onslaught, and remember that you have to multiply its damage by four to compare it to Psionic Touch, since that only activates every fourth attack. |