In an epic Munchkin game with the Unnatural Axe extension, we had an Elf player encounter Santa. Santa is normally a level 9 monster, but that changes by -5 because Santa trusts Elves. Silly Santa.
That player was doing way to well, so someone added Mommy to the fight. Mommy can only be played on a monster of Level 5 or below, or one that is a Baby. We reckoned that since Santa was now a Level 4 monster against Elves, this card could be applied! Mommy adds another monster of the same kind but 10 levels higher.
The poor victim Elf player complained loudly in proper Munchkin fashion, but conceded that our interpretation of the cards was probably allowed.
Was our interpretation correct, and was Mommy playable here? We were going by Santa dropping down 5 levels for Elves here, but perhaps it should not have been allowed because normally Santa is Level 8 instead.
In case you feel sorry for that player, they survived (having slain a monster without help to get of Santa's naughty list) to end up with this hand about two rounds before winning, utterly unstoppable: