THIS GUIDE WILL OUTDATED SOON!
PLEASE USE THE NEW ONE HERE:
This is my list of recommended Heroes for every currently available Outland Portal Boss Fight(Robot Fighter, Northern Dragon, Raged Blood, Burning Phoenix and the Lord of the Caves):
1. Robot Fighter
-> Heroes with DoT (Damage over Time).
2. Northern Dragon
-> Heroes who can fly in the Outland Portal.
3. Raged Blood
-> Heroes who can heal. You don’t exactly need healers, you need to survive, the boss will kill himself after sometime. A complete Tank setup with a little bit heal works fine on this boss too.
4. Burning Phoenix
-> Heroes who can do repeatedly physical Damage at the Outland Portal. Don’t use the Auto Mode on this Boss, save your Ultimates until the Phoenix is in his egg.
Rifleman (activate his Blue Skill ‘Stimulant’ when the boss is in the egg)
5. The Lord of the Caves
-> Needs high single target magic Burst-Damage. Don’t turn on Auto, save the activatable abilities and use them when the Lord of the Caves emerges from the ground!
The best way to kill the Lord of the Caves in the Outland Portal, is by using the Soul Hunter. Wait till you have all your Ultimates ready, activate the other 4 and use the Soul Hunter Ultimate to finish him off, when he got around 50% Hp. It’s an instant kill.