Talia's Flammable Grease

Slick grease covers the ground in a 20-foot square centered on a point within range and turns it into difficult terrain for the duration.

When the grease appears, each creature standing in its area must succeed on a Dexterity saving throw or fall prone. A creature that enters the area or ends its turn there must also succeed on a Dexterity saving throw or fall prone.

The Grease can be lit as an action, when lit creatures in the grease just make a Dexterity saving throw or take 6d6 fire damage a round, taking half on a successful save. Targets on fire may use an action to put themselves out.