Smokestack | Magic: The Gathering
Formats Smokestack is Legal in
Official Oracle Text for Smokestack
At the beginning of each player's upkeep, that player sacrifices a permanent for each soot counter on Smokestack.
Official Rulings for Smokestack
10/4/2004 : Adding a counter is optional. If you forget to add one during your upkeep, you cannot back up and add one later.