"Whereas I was created to protect, the biskelion was created to destroy."
—Karn, silver golem

Serrated Biskelion

{T}: Put a -1/-1 counter on this creature and a -1/-1 counter on target creature.

The List

Duel Decks: Elspeth vs. Tezzeret

{T}: Put a -1/-1 counter on Serrated Biskelion and a -1/-1 counter on target creature.

Weatherlight

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T: Put a -1/-1 counter on Serrated Biskelion and a -1/-1 counter on target creature.

If Serrated Biskelion leaves the battlefield before its ability resolves, you’ll still put a -1/-1 counter on the targeted creature. If the target leaves the battlefield or otherwise becomes an illegal target before the ability resolves, the ability doesn’t resolve and you won’t put a -1/-1 counter on Serrated Biskelion.