Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Oloro, Ageless Ascetic

At the beginning of your upkeep, you gain 2 life.
Whenever you gain life, you may pay {1}. If you do, draw a card and each opponent loses 1 life.
At the beginning of your upkeep, if Oloro, Ageless Ascetic is in the command zone, you gain 2 life.

Smothering Tithe

Whenever an opponent draws a card, that player may pay {2}. If the player doesn't, you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Drogskol Reaver

Flying, double strike, lifelink
Whenever you gain life, draw a card.

Monologue Tax

Whenever an opponent casts their second spell each turn, you create a Treasure token.