|Infuses the caster's melee attacks with magic, drawing from their reserves of magical energy to deal additional damage whenever an enemy is hit. It has no effect when the caster's magic is depleted.|
Infusion will not activate as long as you have 0 MP remaining, but will resume its effect once you've regenerated at least 1 MP.
Status lasts for 8 + 2d<power> turns, and can be extended by casting the spell again.
The effect triggers on any successful melee attack, including attacks not explicitly controlled by the player (riposte and cleaving).
While it's nice to have a level 1 spell that gives you a pseudo-slaying bonus, be aware that it can chew through your MP reserves quickly, and that the additional damage will have little impact against enemies with even modest AC. It can help you deal quick damage to threats in the early game, but don't expect it to help much against orc warriors and the like.
In 0.18, the power cap was lowered allowing scaling more quickly to the same damage bonus as before.
Infusion was added in 0.13.