Volatile Spellweaver

Volatile Spellweaver enters the battlefield tapped
with X +1/+1 counters on it.
{t}, Discard a card, clash with target opponent: If
you win, put a +1/+1 counter on target creature.
If not, remove a counter from target permanent
of an opponent's choice. (You are who targets it.)
Artifact spells you paid {r} to cast have haste.
Spell Mastery — Spellshapers have flash.