Astel, Naturalborn of the Void

Flying

Whenever you counter a spell, you may exile it
under Astel, Naturalborn of the Void. If you do,
put a +1/+1 counter on Astel. As long as three or
more cards are exiled under Astel, it has hexproof
and persist. Spells each opponent cast cost {1} more
to cast for each spell of that type exiled under Astel.

"A malformed star born in the lightless void far
away. A falling star of ill omen."