The user can control the various attributes of the regeneration process, such as the rate and parts to regenerate, and whether the regeneration would even take place. They can control the speed of healing factor of themselves or others, to help close off wounds and regrow limbs without leaving any scars. Conversely, they can slow down the process to increase bleeding and risk of infection.
By controlling the precise location to regenerate, one can prevent unwanted side-effects (i.e. tumors and other disease-infected cells) from increasing, and in fact cause them to die out by preventing cell division. This can also be applied to any matter blocking the wound, allowing one to regenerate around the blockage or eject the obstruction.
By applying the negation on an enemy, this prevents regeneration and even reversing it, causing their cells to enter necrosis when they die without creating new ones. At high powers, one can even negate regeneration of the metaphysical levels (such as Spatial-Temporal Lock induced ones).