I know Sejuani is strong...

Since she's always banned, you guys might want to try Zac. I've had a ton of luck with him, especially as he can just dive the carries no problem. Doubling his knockup on his e means you can chain his ult, manaless, lots of different build paths. All around really solid for me, and sort of my go to jungler right now. Also he's extremely fun to play, which is always a bonus.