Tax Taker
{W}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.)