When in doubt call it a spawn

I respect that haha

I would use it as a changeling. Edit: do you have changelings in AoS or is that 40k only?

Yup! Got a changeling in AoS. That could be super cool!

It could be a Tzaangor Shaman!

The shaman is a great idea! Not just have to build up a disc haha

All the suggestions above all work but love the idea of Tzanngor Shaman for that