What it does
Death Frenzy is a sorcery from Khans of Tarkir, not a keyword—it's a one-time spell effect. When you cast it, all creatures get -2/-2 until end of turn, and whenever a creature dies this turn, you gain 1 life. It's a Sultai (black-green) instant-speed... actually it's a sorcery, so you can only cast it on your own turn.
The nuance people miss: the lifegain trigger lasts the entire turn, not just from the -2/-2 effect. Any creature that dies afterward—combat, sacrifice, other removal—still nets you life. Also, -2/-2 won't kill bigger creatures, so it's a board sweeper biased toward go-wide token strategies.
In Commander, it's a budget board wipe that punishes aggressive token decks while padding your life total. It struggles against fatties and indestructible-heavy boards, but the lifegain can stabilize you against a wide attack.
