Trample
Goblin Mutant can't attack if defending player controls an untapped creature with power 3 or greater.
Goblin Mutant can't block creatures with power 3 or greater.

Protection from white

At the beginning of each end step, if a creature dealt damage by Krovikan Vampire this turn died, put that card onto the battlefield under your control. Sacrifice it when you lose control of Krovikan Vampire.

As an additional cost to cast this spell, discard a red or green card.
Target creature gains trample and gets +X/+0 until end of turn, where X is that creature's converted mana cost.

Trample, haste
Cumulative upkeep (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)