Grease

Spell Type: Utility; Mana Cost: 7 MP; TN: 15
Test: Dexterity (Acrobatics) vs Spellpower; Requirements: Spell Wisp

You create a slick of grease covering an area up to 20 feet in diameter anywhere within 60 feet of you. Anyone within the slick when it is cast, anyone entering the area, and anyone who moves within the area must make a successful Dexterity (Acrobatics) test against your Spellpower or fall prone at each of those times, as they apply. Prone characters may crawl normally.

The grease created by this spell is flammable; contact with fire ignites it, immediately causing 1d6 penetrating damage to everyone in the area. A grease fire burns for rounds equal to your Magic before burning out (which expends the grease), and those inside the area take 1d6 penetrating damage on their turn each round until they exit it. A slick that is not burned persists indefinitely, dispersing only in rain, when appropriately provisioned characters scour it away, or in similar conditions.