Recreating portal effect seen in The Classic event

I’ve been playing the new The Classic event, and i liked how these portals looked, how would i go about recreating the parallax effect? I think it is viewport frames but im pretty lost on how i would make it using viewports.

egomoose has a viewport portal system available, I wish roblox would uncopylock the assets they use in events once their over. the portal system and even game changing cutscene is just amazing and wish I could put it in my games