Voadam
Legend
There are also a ton of not-shadow monster shadow effects in D&D. Some of them have you or the target's shadow do various things or conjures up shadows from nothing.My first tangential thought had been: why is this opponent putting out torches when it could be draining strength? That is why my thought processes then moved toward magic as the cause of the effect.
(Horror genre + Loony Tunes)
But that is a second tangential thought.
Plus to complicate talking about things there is the classic shadow monsters lines of spells that made real seeming monsters with a bit of reality and a lot of shadow plane shadow illusion.
Also in 3e in addition to undead shadows there was the non-undead templates for shadow creatures and dark creatures in addition to the non-undead shadow mastiffs found in many D&D editions.