You create a magical zone that removes dice rolls in a 15-foot-radius sphere centered on a point of your choice within range. Until the spell ends, a creature that enters the spell's area for the first time on a turn or starts its turn there must make a wisdom saving throw. On a successful save, a creature will change any roll to a flip of a coin while in the radius. You don't know whether a creature succeeds or fails on its saving throw.

An affected creature is not aware of the spell and thus a creature affected by the zone can be surprised by there own strength. all dice rolls are changed to a flip of a coin example of this is a heads being a nat 20 and tails being a nat 1. damage wise head is max damage and a tails being a lowest damage.