Make your Ninja lvl 60. No lvl 50 champs in CB. The base stats are low and you can't get Warmaster/Giantslayer mastery before your champs are 6*. The masterie alone will do millions of damage from all 5 champs.
You want the following debuffs at CB (debuffs you have with my suggested team): decrease attack, decrease def, weaken, poison, hp-burn, leech (the latter has to do with Warmaster/Giantslayer, the damage from these masteries can leech. Much more healing the small amount Scyl provides).
You want the following buffs: Increase def, shield, ally protection, heal, strenghten, block debuffs
Sepulcher: decrease atk, increase def, block debuffs (2 turns on a 4 turn cooldown, I don't know if this will block the stun all the time)
Ninja: decrease def, hp-burn
Deliana: leech (disable A2 and A3). You may remove her when you get a better source for leech later on, she can shine better in other parts of the game than CB
Occult Brawler: one of the best CB-poisoners in the game, much better source of poison than Kael
UDK: Aura, backup decrease attack if Sepulcher fails, heal, shields
Not perfect, but you have to work with the champs you have.