Heimerdinger, Revered Inventor

{u}{r}, {t}: Invent.
Whenever an artifact enters the battlefield under
your control, you may pay {2}. If you do, create a
1/2 colorless Turret artifact creature token with defender and reach.
Turrets you control get +1/+1 and have
"Whenever you cast an instant or sorcery spell,
this creature deals 2 damage to any target."