Kotir, Thousand Eyed Fortress

As long as Kotir, Thousand Eyed Fortress is untapped, you do not lose unspent mana as steps and phases end. Instead, put that many flood counters on Kotir, Thousand Eyed Fortress.

At the beginning of your upkeep, if Kotir, Thousand Eyed Fortress has ten or more flood counters on it, sacrifice it.