Feedback Loop

Flash
When Feedback Loop enters the battlefield, exile target nonland permanent.
Whenever an opponent casts a spell or activates an ability, you may pay {1}. If you do, exile that spell or ability. Until end of turn, you may cast a copy of it and may spend mana as though it were mana of any color to cast it.
Permanents and spells you control from exile have "Whenever you cast or activate this, you gain 1 life."
Hexproof.