Unlike most people, when I saw the killer support for primal in Trials of Grodov, I didn't think "Elysian Killers," I thought "Wow, Killer decks don't need to include Time anymore!" Now any faction combo including primal can have a killer/recursion deck thanks to the savagery/bloodhunt/preyfinder/mirror image package.
So far this deck has been more fun than good, but it is VERY fun. I chose to go for Tasbu over Rost because Rost is a big nonbo with Olly and Oizio, and because of influence concerns, however I do acknowledge how attractive it would be to give him killer. Caiphus has been in and out of the deck in testing, he's very high-ceiling/low-floor.
Cirso is a big old pain in the bum for this deck, I'd cut the mirror images and 2 of your least favorite unit for desecrates if he's showing up a lot. Not a fan of permafrost and 4x Vara in the same deck, but do what you must if aggro keeps running you over.