Wow. Yes, great roster. I would save shards for 2x. My guess is you are hurting with gear and obviously need to prioritize 60s.
MAJOR MISTAKE: You have 12 5* and ONLY 2 6* ... this is why you are stuck. The ratio is backwards. You should have more 6 stars than 5*.
1. Miscreated Monster (NEEDS BOOKS)
then the following not sure of order but:
Zelotah(NO BOOKS needed)
Coffinsmasher
Brawler (NO BOOKS needed CB, Dragon20, Golem20)
Doomspriest (NO BOOKS needed)
2. STOP MAKING 50s AND ALL ATTACKERS -- You need support/versatility. No need for a 2nd Kael, Galek, Athel...
3. Put a lock on that 40 armiger, hope that is not a chicken in the oven
Have you done full masteries yet for anyone?
CB short-term: Kael, Brawler (DEF% ACC SPEED - dont waste books here), Coffinsmasher, Roschard, ??? (I think doom or zelotah but they are far away)