Nonflammable grease covers the ground in a 10- 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 have the Prone condition. A creature that enters the area or ends its turn there must also succeed on that save or fall Prone.
RollQuest ships the D&D 2024 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.