Hangman (UST-056) - Unstable

As this creature enters, secretly note a word with six to eight letters.
{1}: Target player who doesn't control this creature guesses the noted word or an unguessed letter in that word. If they guess wrong, put a +1/+1 counter on this creature. Any player may activate this ability.
When a player guesses the noted word or all of its letters, sacrifice this creature.