Kaguma, Sanctuary of Enmity

Kaguma enters the battlefield tapped
{t}: Add {r}
Serenity (Whenever you cast an instant or sorcery,
put a Serenity counter on it.)
{t}, Counter a spell you control with a Serenity
counter on it: Kaguma deals a damage to any
target for each Serenity counter on the countered
spell.