msem-instigator

Target opponent mills five cards. Then exile a card milled this way. You may cast that card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast that spell.
Tether (Then if you cast this from your hand, you may exile it tethered to a creature you control. When it dies, you may cast this from exile without paying its mana cost.)