Conan

The Bone Cleaver is the first boss you will encounter and will reward you with the arm guard, which grants the Song of Death ability.

Strategy:
First you will need to kill the waves of henchmen who will enter the arena.
After that the Bone Cleaver will drop down to your level. He has a standard 4-hit heavy combo, which he can be lured into doing by moving close then running away or dodging (right thumbstick).

Whenever he somersaults, he will do a super shockwave attack, which you will need to jump over. Otherwise, lure the boss into performing his standard combo. Wait for him to end his combo, and then roll up to him and hit him with two or three attacks before rolling away again. Make sure to avoid any bombs being thrown because they do heavy damage.

When the boss has around one-third life remaining, he will start performing a circular swing attack instead of his standard combo. Lure him into performing his circular attack, wait for him to end it, roll up close, hit him with two or three attacks, and then roll back out. Once the boss' life drops to zero, move in close, and go through the displayed button sequence to complete the mission.