Optimize my team

Ok so in my opinion here is what you should change:

- you have 3 stuners in your team and no resurecting unit. You should pick one stunner 2 at most

- sand worm - he is a great stunner but he has low LUK, you should use bard tome on him in order to give him some extra chance to land his stuns. You don't need other stats from the tome since his sole role is to stun. Leave damage to your other nuking units. The problem with sand worm is that even with the Bard tome, his LUK is still low and his stun will ofently be resisted by dungeon boss creatures. In order to counter this, you should use a buffing unit together with sand worm. Valkery is the best buffer in the entire game, use valkery special first(it will buff all stats +40%) and then use sandworm. The drawback of this is that it takes 2 rounds (buff, then stun) and dungeon bosses can start with a special attack in round 1 so it will leave you vulnerable in round 1 when you place the buffs..

- enraged keeper is a good stuner with a 4 rounds stun(5 rounds if fully awaken) and on top of that he also has a heal, he can fit very well the main stunner role, his LUK attribute is high enough
- Blue Ancient Dragon - he is good vs red creatures, but beside this his damage is not so great and his stun lasts only 3 rounds
- corupted angel is your nuking creature, +10% ATK tome on him
- Pheonix is a perfect creature, nuking power, slef heal and resurects himself, he can solo some dungeons so definately keep him in the team

So in order to upgrade your team, you will need a resurecter and a main healer (Enraged Keeper is not enough to heal by himself but Astral Watcher can perfectly fit both of the roles and on top of that he provides mana!).
Your new team could look like this:
- Pheonix - nuker
- Corupted angel - nuker
- Enraged Keeper - secondary healer and main stunner.
- Astral Watcher - Main healer, resurecter and mana booster
- and for the 5th slot you can use either a buffer like Valkery to complement your other creatures with +% stats, or the blue ancient dragon to kill the enemy pheonixes which are present in almost any decent defense, or a Sphinx to use the silence + stun lock combo
*unfortunately I don't see any space left for the Sandworm with the above mentioned team setup, he should be better used for defending. As I was saying, Sandworm needs a buffer to boost his LUK stat, without it his stun gets resisten too often(I also use him and without the Valkery buff his stun is almost always resisted).

Probably you already know the Mantastic chanel, but this two links are useful - a tier like classfication for OFFENSE & DEFENSE creatures:
mantasticcq.wordpress.com/2017/06/27/legendary-creature-dungeon-defender-tier-list/
mantasticcq.wordpress.com/2017/06/30/legendary-creature-dungeon-offense-tier-list/