We keep getting more and more mega bosses so you might want to start working on an anti-mega boss team.
You can check out my guide here
viewtopic.php?f=8&t=2937
#ShamelessPlug
It's a step by step guide to make an anti-mega boss team and luckily, you have every single unit required for the build. Based on your screenshot, you can make use of Zealot Leon, Gladiator Drake, Berserker Vincent and Spiritwalker Kahuna. I was underwhelmed with Dragoon Drake so I don't recommend working on him but that's just me! You also would not want to waste a Darrion to just become a Blood Knight so I suggest just using Gladiator Drake.
Being a new player, this anti-mega boss team can also help you alot clearing Legendary Capitol 3 and Legendary Story 24-3.
To be honest, I kinda of agree that Dragoon Drake is abit over rated as a DD. Yes he complement the SDD team with his aura, but that it. And his complement is limited to his limited attack range with a straight line, as compared to berserk with a spread attack.
Because if his main purpose is to complement the team as a mega boss cleaner, his attack range is a setback.
Furthermore, other 5* Dragoon have better ulitity skill than him where debuff can be left to other heroes like tank or healer.
As a main attacker that jump into a group of enemy, the debuff doesn't serve any purpose to hinder their progress, like vincent or Freya Dragoon where they stun the enemies for 2 turn.
So very clearly he makes us feel like he is more of a support role than the main DD role, that his Dragoon does not give.
On the other hand, his gladiator drake prove to be a better support attacker with his life leech and debuff, which make sense as he won't need to jump in to debuff and yet his teammate can benefit from him.
If compare with other heroes that can serve the purpose, darrion blood knight serve as a superior tanker that can survive very long, victoria is a secondary replacement to darRion, Leon purpose is to do pull in, and drake purpose is to provide the debuff.
In short, you won't need to have a ares drake if you going to use him as a support attacker but a zeus or a kratos drake can serve him well.