Spirit Awakening is a passive ability introduced with the 5th Generation of Honor Units:

The skill is applied from the Time Shop and increases the max Gold Level of units. Each 5* Spirit Awakening Unit increase this limit by 5, while 6* units increase the limit by 10.

The limit without related pets is 100. This can be reached using only a single unit or a mixture of them all.

Late game the maximum gold limit of units often far exceeds the amount reachable due to economy limits. As such this buff is very situational depending on how close to the maximum Gold Level the player is.

Limit Break

Upon reaching 5*, the Pets for the 4 Spirit Awakening units increase the maximum Limit of Spirit Awakening. The 4 pets in question are:

Each pet allows it's Hero Couple (when evolved to 6*) to increase the Limit of Spirit Awakening by 5, with this increase limited to 25 per unit.

Thus, to reach the maximum all 4 pets are required at 5* along with 20 Senior (6*) units (5 of each). This increases the Limit for Spirit Awakening from 100 to 200.

Additionally, since this requires 20 6* Spirit Awakening units, and each 6* unit increases Spirit Awakening by 10, maxing the Limit Break skill also maxes out Spirit Awakening itself at 200.

TLDR - To maximise Spirit Awakening the 4 Pets (Bunny, Cora, Winky and Wakong) must be 5* and 5 Senior Units of each Hero Couple (Alchemist, Lich, Pilot and Wyvern) is required.