Eruption Of Speed

Little Shrubby's Seven Beast Burst Innate skill was incredible and would enhance all of his abilities by several levels.

But doing that would also exhaust him greatly, and force him into a dormant state. The last time Little Shrubby had used the skill, it had turned him into a seed and left him dormant for years. 

All that had happened in the Xiaofan World when Little Shrubby wasn't even in the Immortal realm. And now that he was an Immortal beast, his strength had increased by several levels and the same could be said for his bloodline.

As such, the Innate Skill had improved too and there was no telling how great its exhaustion would be at the end.

There were many possibilities to it. 

There was a chance that Little Shrubby might be totally fine and wouldn't enter a dormant state at all. But there was also a chance that he would fall into a long dormant state that might take many years to overcome.