Hastur, The Unspeakable

Hexproof, Fear, Indestructible
When Hastur, The Unspeakable attacks successfully, you can choose an opponents,
creature and put a yellow sign counter on it
if a creature has a yellow sign counter on it,
that creature has a -2/-2 counter on it
you can only have one Hastur, The Unspeakable
in your library