Mystery Booster 2

Sorcery

Create a 2/2 white Monk creature token.
Coststorm (When you cast this spell, copy it for each different mana value among other spells and lands you've played this turn.)

Friarball

Creature — Rat Advisor

Whenever an opponent pays a tax from a spell or permanent you control, create a number of Treasure tokens equal to the amount of mana they paid. (This happens each time a spell you control or an ability of a permanent you control causes an opponent to pay extra mana. Cards that can tax opponents include Mana Tithe, Esper Sentinel, and Ghostly Prison.)