War frenzy

Creatures you control enter the battlefield with X +!+! counters, where X is how much life opponents lost on your last turn.
At the beginning of your upkeep, flip a coin. If you win, create X 1/1 red goblin creature tokens with haste, where X is the number of lands your opponents control. If you lose the flip, sacrifice all creatures you control, and you lose half your life, rounded up.