Ranshi, Lucid Dreamer

As long as Ranshi is tapped, noncreature spells you cast cost {1} less to cast.
Whenever you cast a noncreature spell, if Ranshi is untapped, you may tap it. If you
do, exile the top card of your library face
down. You may look at and play that card
for as along as Ranshi remains on the battlefield.