Hastur, the King in Yellow

Lifelink, Deathtouch, Flying

Whenever a player casts a non-cosmic spell,
you may put a +1/+1 counter on a creature.
Whenever a spell or ability an opponent controls targets a permanent you control,
Hastur deals damage equal to its power to that player and you may proliferate.

"Woe to him who is so foolish as to speak his name!"