Grenade, Foam

When detonated, a foam grenade fills a 10-foot-radius sphere with slippery, fire-retardant foam. Open flames in the area when the grenade explodes are immediately extinguished. For the next minute, the ground in the area is difficult terrain. A creature in the affected area or one that enters the area for the first time on a turn or begins its turn in the area, makes a DC 10 Dexterity saving throw, falling prone on a failure.