Intervention Summons

Reflex {r}{p/w} - You are declared the target of an
opponent's spell or ability (A card may be cast for
it's Reflex cost anytime you would cast an instant
if these conditions are met)
Until the end of the current turn, you gain
hexproof and your life total cannot change
as a result of combat damage. If Intervention
summons was a Reflex cast, exile target creature
you control.