This is a weird one. Because it’s sometimes a template and sometimes isn’t, and when it’s a template it goes by an L name but creates creatures that begin with W, but it’s a template so broad that each creature you make with it is technically three creatures, it’s not like anything else this month and arguably not like anything else in D&D. It might even be the thing this month mostly likely to be a PC. With all that going for it there was no way I was going to talk about witchknives instead.
D&D has several varieties of were-things. The most common are werewolves, but the rulebooks also have werebears, wereboars, weretigers, wererats, and occasionally dire versions of the same. Lycanthropy is usually a template that lets you rub a humanoid and an animal together until a monsters comes out, and though the resulting creature varies wildly in size, skills, and combat potential it’s universally better than the originals. Were-things don’t always lose their minds under the full moon, but they do always have DR against everything but silver, D&D’s…well, silver bullet for shapeshifters.
It’s this variability that makes them worthwhile. Need a big, strong monster who can throw wagons at the party? Combine a hill giant with a bear! Need a tricky sneak who can survive a few hits? Combine a halfling with a rat! Need a veteran of the Underdark who avoids capture by pretending to be an innocuous animal? Combine a dwarf with a giant bat! Most templates let you turn the original creature into something else, but lycanthropy can change any single creature into dozens of others. They usually have class levels to augment them further, from the obvious orcish werewolf barbarian lord to the significantly more ridiculous merfolk werefrog paladin. And you can add them to a group or adventure based on their race, their animal, their class, or anything else you want. They’re a blank slate you can use to accomplish nearly anything.
In fact, that freedom gets even broader when you strip away the lycanthropy itself and pretend you’ve made up a new creature (take a drink). The hybrid form of a lycanthrope keeps it mostly human but gives it several of the animal’s abilities. Consider the wererat, with its natural bite attack that inflicts disease. That can just as easily be a feral sewer-dwelling creature who sneaks around and ambushes lone victims. You only need to make a few changes. First, strip away the DR or change it to something more flavorful (“DR 5/attacks made in sunlight”). Second, if you don’t specifically want the monster to walk among townsfolk or pass unnoticed as a rat, take away the transforming entirely. It’s not a meaningful part of the CR, and if it doesn’t fit your flavor, don’t bother with it. Third, feel free to ignore the curse of lycanthropy it can inflict with its attacks. It’s probably safe to assume most DMs would be happier without the headache of accidentally cursing their players with combat bonuses. With those gone, there’s nothing left tying you to a specific transforming common-knowledge creature.
I’ve done this several times, especially using the 3E version of the template where you added the animal’s Hit Dice to the base creature’s. Remember when I said I’d spent forever trying to come up with a template for elite creatures? This is really, really close. I don’t always like the amount of number-crunching it takes, and I don’t always want to give tiger powers to my elite elven necromancer, but you could do worse than adding a bunch of levels onto a creature in a way that doesn’t give them overpowered monster abilities.
The only problem I see with lycanthropes, besides the bookkeeping concerns above, is that they’re all physical creatures. There aren’t any werewolf clerics or sorcerers because werewolves are about hitting things, not magic. It’s a bit of a shame, though I feel its limitations make it stronger. “Combine a humanoid and an animal” is already a task with a plethora of options. We don’t really need to make it harder by tacking on magical options too. The lycanthrope does one thing and does it well in an uncountable number of ways. That suffices.