No, it's definitely NOT IC2. It's been out since as far back as I remember and it has never added mob types afaik. I'm afraid I can't make a real guess without knowing the full mod list, but preliminary scrutiny would say some sort of magic mod.
I do not know about those wings, but I can tell you that those pumpkin helmets are a vanilla feature. I mean, the fact that mobs spawn with a pumpkin helmet at 31/10 is a little know vanilla feature.
Can be dangerous as those mobs don't die in sunlight, so they might unexpectedly attack you on the surface at day, wandering out of a nearby cave.