+Mystical (4)
This spell costs less to cast if it targets a blue spell.
Counter target spell unless its controller pays .
Search your library for an instant card or a card with flash, reveal it, put it into your hand, then shuffle.
Flashback (You may cast this card from your graveyard for its flashback cost. Then exile it.)
You may cast Mystical Tether as though it had flash if you pay more to cast it.
When Mystical Tether enters the battlefield, exile target artifact or creature an opponent controls until Mystical Tether leaves the battlefield.
Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.
Gatherer works better in the Companion app!
(You may cast this card from your graveyard for its flashback cost. Then exile it.)