Sigma, Astrophysicist

Flying
{1}{w}{u}: Counter target spell that targets Sigma,
Sigma gains +0/+X where X was that spells mana
cost
{2}{b}: Sigma deals 2 damage to target creature,
tap it, put a stun counter on it
{3}{w}{u}{b}: Creatures your opponents control can't
block creature without flying until end of turn
{3}{u}: Create a 0/4 legendary artifact creature-
barrier with defender