Ratcatcher
The Unearthed Arcana of a few weeks ago featured an alternate version of experience granting you a set amount of experience for every opponent defeated. And someone immediately commented about how you could just go and kill twenty chickens and gain a level. This is a very minor twist on the classical “bag of rats” rule loophole, where a character carries a sack of rodents to execute whenever they need to trigger an ability that requires killing an enemy.
I do wonder at the logistics of this. Rats need to be fed after all. And its not like you can just hit up a lab rat wholeseller.
Well, actually, a while back, a certain Harry Potter fanfic (by Starfox5) I read had a scene where a bad guy attempted to cast a spell inside Hogwarts, using the sacrifice of a ‘rat’ (actually a Muggle transfigured into a rat).
It probably wouldn’t be effective as an ‘after killing an enemy’ effect, but it would be amazing fluff to have an evil spellcaster or blood mage pull out a live animal, or still-living preserved organ, and slice it open as part of casting a spell.
In our groups of players there is usually the agreement that an enemy is “someone or something which actively pursues the aim to harm the characters, willingly or not, and has the means to do so”. Therefore rats are not a threat, unless it is a whole swarm of them, or a few giant ones…
But I witnessed first-hand a wizard charming local guards to have them follow the group, and then order them to attack the barbarian to fulfill the aforementioned requirements. Also, being a huge fan of Star Trek, he made them wear red shirts first…