Transmutation [see text]
Level: Sorcerer 5, Wizard 5
Components: S
Casting Time: 1 swift action
Range: Personal
Target: Your breath weapon
Duration: 1 round
Your foes, prepared for your terrible fiery breath weapon, are caught off guard as you exhale a cone of caustic acid in their surprised faces.
For this spell to function, you must have a breath weapon, either as a supernatural ability or as the result of casting a spell such as dragon breath. When you successfully cast this spell, you choose one type of energy other than that normally associated with your breath weapon: acid, cold, electricity, or fire. You can modify your breath weapon to use the selected energy type instead of its normal energy type. For example, a dragon whose breath weapon normally deals 16d10 points of fire damage could use this spell to produce a cone dealing 16d10 points of acid damage instead.
When you use this spell to produce acid, cold, electricity, or fire energy, it is a spell of that type. For example, breath weapon substitution is an acid spell when you cast it to change your breath weapon to deal acid damage.
Source: Spell Compendium, page 39. Previously published in Draconomicon, page 78.