Self Controlled Twilight Dragon

Generally, the Body Cultivators who reach the Emperor Realm have bodies as strong as the spirit beasts of the same realm.

There were even cases where some Body Cultivators had stronger bodies than the Spirit Beasts. The 100 Old Cultivators were not Normal Body Cultivators but Divine Body Cultivators with thousands of years of battle experience.

Even though they were low-level Emperor Realm Divine Body Cultivators, they could easily take the low-level Emperor Realm Spirit Beasts with their raw strength, not to mention using the Cultivation Techniques.

Hence, the first layer of Dragon Coilers was having an easy time dealing with the first round of the beast horde.

Even though they could have killed more, they didn't go all out from the beginning; instead, they would let a spirit beast pass through them for every three Spirit Beasts they killed.