Soul Absorption

“	...cast Soul Absorption on you which reduces your HP by 5% of your Maximum HP every second.	„
—Call of the Light

“	When the Girgashiy's HP is low, it will start using Soul Absorption. This will cause a shadow of you to appear and move toward the Girgashy. If your shadow reaches it, it will heal some damage and you will be knocked out instantly.	„
—Realization

These are two entirely different effects...

If I must stress this out again, the Girgashiy in Call of the Light does not use Soul Absorption, and it doesn't cut HP by 5% per second. That's Holy Contagion.