A flask of alchemical oil makes a patch of floor almost impassable—and it burns nicely, too.

Daily   ✦     Zone
Standard Action      Area burst 2 within 10 squares

Requirement: You must have an alchemy case on your person.

Effect: The burst creates a zone of difficult terrain until the end of the encounter. Any creature that enters the zone must succeed on an Acrobatics check against a DC equal to 10 + one-half your level or fall prone. Each creature that falls prone in the zone gains vulnerable 5 fire until the end of its next turn.

Published in Dragon Magazine 399.