I see Krama has team suggested there... but I would go a different way on a few champs.
First off, I would make sure the champs I am using have their proper Warmaster/Giantslayer masteries. This makes up a huge damage difference, especially when you're trying to push having a 2-3 key for the first time. Or even just a 4 key. lol
Giscard is a great recommendation. He'll bring a Dec Atk for the CB, as well as nice Inc Def and Inc Atk buffs for your team. He is also a strong champ in Faction Wars and earlier Tag Team, so he's not a wasted build to 60.
Toragi ofc is the CB king. His Ally Protection, coupled with heals and poisons, make him an excellent addition to any killable CB team. He brings more Dec Atk for CB to ensure it is always on him.
Anax is the better DPS for a killable CB team. His Inc Def and Inc Atk passives make it easier to keep him alive when he takes a solid shot, and he can get an extra turn at 10% of his health, enabling another huge Warmaster proc of healing from Leech. He also has about 100 extra base defense, and his self healing attack on his A3 is quite good (better than Fayne's self healing)
Speaking of Leech, we need it. While Krama suggested Sachi for Leech, I would recommend Runekeeper Dazdurk, who has Leech, an Inc Attack with TM fill, AND a full team cleanse and heal on a 4 turn cooldown. This makes him EXCELLENT for making your future teams affinity friendly in the proper 4:3 tunes. He's great in most areas of the game as well, and will shine in FW.
Finally, we get UDK for shields and absorbing the stuns as much as possible, redirecting quite a few even when he's not the stun Target. His self healing and naturally high defense should make up for the regular damage, enabling him to take the Max HP based stun attack.
Also, if you're just pushing NM right now, and not pushing UNM, the key isn't to be all super sync'd up or anything. I wouldn't stress overly much about speeds. Just get those champs built up first, then we can look at a good 4:3 speed tune to slot everyone into that works with Runekeeper's TM boost.
If I was starting with any rankups, I would rank up Anax first, followed by Giscard then Runekeeper, swapping Anax out for Geomancer, Giscard for Ursala, then Runekeeper for Apothecary.