One of the PCs in my current Concord game (of our 13th Age campaign) was recently bitten by a werewolf.
Because I'm such a nice GM I’m using the werebeasts stats from 13 True Ways and the Cursed Bite ability. Basically, that means that the party's PC (a human wizard) will become a new werebeast in the next full moon.
Of course, there's an artifact in my campaign that just happens to summon the moon closer to the Dragon Empire. So, while the wizard was very happy with all that Overworld mojo increasing his spells (due the moon’s proximity to the mortal realm), he was considerably distressed about his new "condition".
I wanted the lycanthropy rules for afflicted PCs to follow the 13th Age's ethos: they must be fun, simple and "gameable". However, I was also in a very short time to tinker something more robust, so I stole the rules.
Instead of just saying that the wizard morphed into a full werewolf on the spot when the full moon was up, I created a table, based on the Wendigo's Hunger effect (from page 211 of the 13th Age Bestiary).
Here it is:
Lycanthropy: those affected by a Cursed Bite attack are susceptible to a series of special triggers and must save (usually at 16+) or roll on the following table (1d6) once per turn.
Common triggers are things like seeing the full moon, smelling raw meat or witnessing a bloodshed battle. It's safe to assume at least 1 trigger per lethal combat. Personally, I like to trigger an afflicted a PC, during combat, at Escalation Die 3 or 4 (when the combat is well underway and there're probably a few fresh corpses scattered around the scene).
1–2: The afflicted PC takes 10 damage as the lycanthropy distorts his body and inflicts pain. If the afflicted PC falls to 0 or less hit points, he/she shapechanges into a full werebeast (controlled by the GM) and probably attacks everyone around him.
3–4: The afflicted PC makes a basic unarmed melee attack* against the nearest or most vulnerable ally (moving if necessary). If there's no target nearby, the afflicted PC howls, rages, destroy something or executes a similar classic and cinematic lycanthropic action.
5–6: The afflicted PC makes a basic unarmed melee attack* against another werebeast, an animal, monster or equivalent savage creature in near range, which he/she seems as a rival (yes, the afflicted PC can choose target). If If there's no target nearby, afflicted PC howls, rages, destroy something or executes a similar classic and cinematic lycanthropic action.
*If the GM is feeling generous (or devilish), the afflicted PC’s basic unarmed melee attacks now do at least 1d8 or 1d10 per level (either because of a lycanthropic bite or claw).