I have no experience with unkillable so I'll refrain from commenting on that part but - I can't see any way in which Rugnor works on a CB team. His passive is going to completely throw off your rotations.
His passive only reduces the cooldown of his A2 and has no direct effect on the turnmeter in any way. His A2 has a turnmeter boost, but you can disable this skill and use Rugnor just for the combination of leech (A1), and decrease def + weaken (A3).
I guess you need the leech debuff, because the damage from the stun hit is eaten with only one Maneater and the hp-bar has to be filled up before the next stun.
I currently have Rowan as my stun Target, but I need a second one so that I don't have to keep changing gear on her for my various Budget Unkillabke teams. Not sure when I will get a second Maneater...
My unkillable team is tower warcaster shipi anax skullcrusher As long as skullcrusher has his counter attack up on the other champs he will always be the stun target so he wont trigger counter attacks i hope this helps if he is fully booked he will only have the counter attaxk down for one turn unless you use a reflex set up