Another Day
The bigger the changes that took place in the body of Ash, the bigger burden on her ability it was.
It was usually accompanied by greater discomfort when her body morphed into shapes and sizes far too different to her own.
The amount of Life Energy depleted faster in order to complete such a big change while sustaining it was more taxing for someone of her weak capabilities.
There may have been a little growth with her Life Energy from ending the life of the black Ferret but the amount was not enough to make that much of a difference.
Those that stole from others could not exactly take everything from their target since such techniques could not achieve such a feat.
If it was so easy to gain power by killing small animals or a couple of people then people like herself would be everywhere.
A small percentage of a life would be taken unless certain conditions and rules were met to allow for a little more.