Q: Dear Sage,
Can an undead creature enter a rage? If so what benefit (if any) does it gain from the Constitution bonus?
A: An undead creature can indeed enter a rage. Since undead creatures don’t have a Con score, the bonus to Constitution provides no benefit (and thus the undead doesn’t gain any extra hit points when raging).
You didn’t ask about duration, but it’s worth noting that since the modifier for a nonability is +0 (MM pg. 312), an undead creature’s rage would last 3 rounds.
About the Author
The Sage is a mammal classified in the bear family, Ursidae, native to central and southern China. Debate continues as to whether he is truly a bear or more related to the raccoon rather than the bear, or perhaps in a family of his own. When not eating bamboo and answering rules questions, he works under the nom de plume of Andy Collins as an RPG developer in Wizards of the Coast R&D, where his development credits include Complete Mage, Dragon Magic, and the Player's Handbook v.3.5. He can be easily recognized by his large, distinctive black patches around the eyes, ears and on his rotund body.