I'll share another solid team for clearing Hera. This team is much easier to assemble, but slightly more stressful than my Amaterasu + Odin team. You'll have to manual heal each turn. On the plus side, it's a team that is not luck dependent as well
The team requires the above mentioned members.
1.) A 50% dark resist monster. Dark resist dragon is preferred because it has AOE skill.
2.) Two Sirens with max skills (Or 1 Siren + 1 mermaid, as long as they have max skill).
3.) 1 Rainbow Keeper for HP boost and damage reduction skill.
4.) A poison monster.
5.) An Odin friend.
6.) HP of 8220 and above, but it should be as high as possible.
You can swap Dark resist dragon for a Abyss Neptune. If so, then you're free to replace Lilith with a machine dragon or a Dragon with AOE skill.
The rest is as per normal. Store the gems required, AOE and charge your skills. Rinse and repeat.
For the solo bosses, just chain as much combos as you can so that the recovery gems will replenish.
This is a much more practical team to assemble, and all the monsters required are useful monsters which you should have. For players aiming to clear Hera, I'll recommend this team.