Ioun, The Knowing Mistress

Whenever Ioun is put in the graveyard or exile
from anywhere, put it into your library third
from the top.
You can look at the top of your library at any
time, and you have no maximum hand size.
You can play lands and cast spells from the top of
your library. Rather than pay mana for spells cast
this way, you may discard a card that shares a
color with that spell.