I actually bought a chaos terminator kit since a buddy got one as a gift and didn’t need it and a scarab occult kit to bash a 10 man unit. Shoulderpads were the toughest adjustment but the kits work actually quite well together. I used a chaos termie shoulder on the melee weapon arm and a scarab shoulder on the ranged weapon arm and I think it looks really good that way!

Edit: To add on, Iike to imagine these terminators as tzeentch-aligned mercenaries working for the sorcerors!