Kaziel's Doom Scale

Kaziel's Doom Scale enters the battlefield with X time counters on it. At the beginning of each of its controller's upkeeps, remove a time counter from Kaziel's Doom Scale. When the last is removed, sacrifice Kaziel's Doom Sphere. Then exile all permanents and all graveyards.
{2}: Add a time counter to Kaziel's Doom Scale. Activate this ability only once per turn. Any player may activate this ability.