Mad Alchemist( Player's Handbook II, p. 94)
You are an expert at using alchemical items. Through experimentation, research, and your careful study of the art of alchemy, you have learned to make the most of items such as alchemist's fi re.
The Mad Alchemist feat grants you access to three special tactical maneuvers. Distracting Blast: If you ready an action to throw a thunderstone at the square an opponent occupies, you can disrupt his actions. The sudden bang from the stone's detonation ruins your foe's concentration, possibly spoiling his attack or his attempt to cast a spell. If the target of this blast was casting a spell when you threw the thunderstone, he must make a Concentration check opposed by your Craft (alchemy) check. If you succeed on this check, his spell is ruined. If the target was not casting a spell, he must make a Will save opposed by your Craft (alchemy) check or take a -2 penalty on attack rolls, checks, and saves until the beginning of your next turn. Fiery Blaze: To use this maneuver, you must fi rst strike a creature with a container of lantern oil or alchemist's fi re. On your next turn, you must strike the creature with a spell or weapon attack that dealsfiredamage. If you do so, the creature takes an extra 1d6 points offiredamage and catches onfireif it is not already in fl ames. Tanglefoot Defense: By tearing open a tanglefoot bag and spreading its contents across an area, you can create a vexing barrier that hinders an opponent's approach. As a standard action, you can transform a single square of clear terrain into diffi cult terrain through the use of a tanglefoot bag. This effect persists for 10 minutes before the tanglefoot bag loses its potency.