Izmel, Tomb Raider

Assign - Curse of Osirmeth
First strike, Menace
Whenever Izmel, Tomb Raider deals combat damage to a player, choose one: Create a colorless artifact token named Gold. It has "Sacrifice this artifact: Add one mana of any color to your mana pool." ; Or exile the top card
of your library and you may play it until your next turn.