Chapter 256- Sunfire Vitality Pill

Amon urged, even pushing his body practically. Yang Chen had no choice but to go through with it. He had heard about battle companions, demonic beasts who have formed a soul connection with a practitioner.

Once a soul connection is formed the practioner and the demonic beast become a companion of sorts helping each other and fighting together.

Suppose in a situation where one is fighting against their opponent and is at a back foot of sorts, they can summon their battle companion and quickly turn the situation into a 2V1 for the other party.

Thus pulling them into a disadvantage. There are many other advantages to having a battle companion like using it as a mount or as a guardian when you are at a critical juncture of your cultivation and so on.