Mutavault

Each other Warrior creature you control enters with an additional +1/+1 counter on it. Each creature you control with a +1/+1 counter on it has trample.

Electrolyze deals 2 damage divided as you choose among one or two targets. Draw a card.

Flying Whenever you draw a card, Niv-Mizzet deals 1 damage to any target. T: Draw a card.

Trample, haste At the beginning of the end step, sacrifice this creature.

Counter target spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)

Other Elves you control get +1/+1. G, T: Create a 1/1 green Elf Warrior creature token.

(B/R can be paid with either B or R.) 3B, Discard a card: Target creature gets -2/-2 until end of turn. 3R: Create a 2/1 red Goblin creature token with haste. Exile it at the beginning of the next end step.

First strike, protection from white