Ghostly Pilferer

Whenever Ghostly Pilferer becomes untapped, you may pay {2}. If you do, draw a card.
Whenever an opponent casts a spell from anywhere other than their hand, draw a card.
Discard a card: Ghostly Pilferer can't be blocked this turn.

Azorius Aethermage

Whenever a permanent is returned to your hand, you may pay {1}. If you do, draw a card.

Magus of the Tabernacle

All creatures have "At the beginning of your upkeep, sacrifice this creature unless you pay {1}."

Aether Barrier

Whenever a player casts a creature spell, that player sacrifices a permanent of their choice unless they pay {1}.