Sylph
Fickle
Wisps and spectres come to mind as an initial option. It's difficult as most creature variants of affinities affect the body of the creature rather than being casted externally. Light isn't very useful as a defence mechanism (compared to similarly non-solid elements such as fire or lightning), so naturally there aren't as many creatures attuned to it.Okay, so in a general sense they are all rare, but this is good seeing as the Light Affinity, if used properly, is a very effective tool. In any case, I would like to discuss possible options for the light affinity based creatures that could add to his strategy. A.K.A. Light affinity creatures that he could cast through.
As it turns out, he is gonna be a rare beast collector. lol
The reason I mention the rifts is they can often lead to realms or places where energy and magic don't work in quite the same way as the current world, so light can become a much more viable defence.
It's definitely an area I'll give some thought to! Potentially there might be some creatures who learned to use it as a way to distract or blind predators.