Mello, Belligerent Avenger

Menace
When Mello, Belligerent Avenger is blocked, you
may put a -1/-1 counter on it. If you do, Mello
gains indestructible until end of turn.
{2}{t}: Remove all counters from target creature, artifact, or enchantment.
Sacrifice Mello: Destroy target creature.
I'm not a tool for you to use to solve the puzzle.