When the soul overcame the third power, she ascended and saw the forth power.
It took seven forms:
The first form is darkness,
the second, desire,
the third, ignorance,
the forth, death wish,
the fifth, fleshly kingdom,
the sixth, foolish fleshly wisdom,
the seventh, angry person's wisdom.

These are the seven powers of wrath.

I believe what Mary is calling the third and forth "power" is what we would call the third and forth dimension.
The third dimension is where we live, so we are familiar with it.  The forth dimension is the home of the fallen angels, the devils and demons.  The seven forms are the tools they use to control us and get us to do their bidding.
These are powerful tools, difficult to resist, but God and His Angels have tools as well which can help us resist.