I've seen a lot of Cubimals lying around in Cebarkul, and I can't decide if they're left there for players to pick up and use or if they're the result of people leaving, logging out, or getting kicked off before their champion returns to their bags.
I'll keep an eye out for NightRook. I hope you get it back!
If not, I'd be happy to find a way to shower you with rook cubimals by the end of next week. It wouldn't be the same, but at least it would be amazing.