Crackdown

Nonwhite creatures with power 3 or greater don't untap during their controllers' untap steps.

Surge of Strength

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 mana value.

Mephidross Vampire

Flying
Each creature you control is a Vampire in addition to its other creature types and has "Whenever this creature deals damage to a creature, put a +1/+1 counter on this creature."

Energy Arc

Untap any number of target creatures. Prevent all combat damage that would be dealt to and dealt by those creatures this turn.

War Barge

{3}: Target creature gains islandwalk until end of turn. When this artifact leaves the battlefield this turn, destroy that creature. A creature destroyed this way can't be regenerated. (A creature with islandwalk can't be blocked as long as defending player controls an Island.)

Paladin of Prahv

Whenever this creature deals damage, you gain that much life.
Forecast — {1}{W}, Reveal this card from your hand: Whenever target creature deals damage this turn, you gain that much life. (Activate only during your upkeep and only once each turn.)

Kaervek's Purge

Destroy target creature with mana value X. If that creature dies this way, Kaervek's Purge deals damage equal to the creature's power to the creature's controller.

Ritual of the Machine

As an additional cost to cast this spell, sacrifice a creature.
Gain control of target nonartifact, nonblack creature.