I put together a team similiar to a CC one I saw, but it only works like 50% of the time, if that. Needs tweaked, but DID get me through hard 10. i'm confident I can get it closer to 100% with some books and glyphs.
Razelvarg lead (and goes first) - 3 hits on his a1, 250 speed but he gets sped up by boss to go first.
Longbeard goes second - 270ish speed can be any ally attack champ, but he goes with everyone including Razelvarg and his multi hitting a1.
Fahrakin goes 3rd - second ally attack, can probably be anyone again, but with razel and the rest of the team he gets the sheild down on this attack. Doesn't need accuracy or anything, just the proper speed.
Yakarl - goes after the first 3, hes important because he freezes the waves so you can make it through, AND he puts a decrease speed on the boss. If his decrease speed fails to land after the shield is down, it's over. He also reduces TM. Accuracy and speed are the stats we need.
Gnut - goes after first 3, locked into a1 for the boss so he keeps reducing TM (sucks cause I really want to use that a3.)
Gnut and Yak are in the 260s i think.
Team uses 2 fusions, a shop frag champ, and then if you have 2 aly attack's you'll be fine. I don't have card/valk so I was happy to see this pop up.