Pompeii

Most Planechase cards fire their effect and reset the moment you leave; this one keeps score. The eruption counter accrues on arrival, again every upkeep, and again on each blank planar roll, so the plane spends the whole time you occupy it winding up a spring. The payoff is the design's cleverest move: chaos does not merely trigger an effect, it detonates everything you have been quietly stacking. The damage to every creature and player scales with a number you have been feeding for turns, and unlike most board wipes there is no way to know in advance how large it will be, because it depends on how long the planar die has cooperated. The land sacrifice on top turns a big roll into a genuine setback rather than a spectacle, and the forced planeswalk means the volcano cleans up after itself, resetting to zero for whoever inherits the plane next. It is a rare Plane that punishes patience at the table: the longer everyone stalls on it, the worse the eventual eruption, and the die decides when. The Scry 2 attached to the blank roll is the small mercy, smoothing your draws while the counter ticks upward, a quiet reward for the same event that brings the reckoning closer.