Riftgale Graftling

Vigilance
Whenever Riffgale Graftling enters the
battlefield or becomes tapped, each player
Chambers 3. (They exile the bottom three cards
of their library to the sanctum. Any player can
cast spells and play lands in the sanctum.)
{t}: Target player who cast a spell from the
sanctum this turn discards a card or
draws a card.