After being unhooked or unhooking yourself, Decisive Strike activates for the next 40/50/60 seconds:

When grabbed or picked up by the Killer, succeed a Skill Check
to stab the Killer and escape from their grasp.

Stuns the Killer for 4 seconds

Causes you to become the next Obsession

Decisive Strike is deactivated once the Exit Gates are powered.
Decisive Strike is disabled for the remainder of the Trial after use.
Decisive Strike is deactivated prematurely when performing a Conspicuous Action and remains disabled for the remainder of the Trial.

Increases your chance of becoming the initial Obsession by increasing the default value by +100 %.
The Killer can only be obsessed with one Survivor at a time.
Decisive Strike in Dead by Daylight is a controversial perk that has sparked debates within the community due to its perceived unfairness, especially from the perspective of the Killer. While it provides Survivors with a tool to escape after being unhooked, the mechanics of the perk can be seen as imbalanced and disruptive to gameplay for several reasons.

First and foremost, the very nature of the perk allows Survivors to escape from a Killer's grasp through the success of a Skill Check. This mechanic not only grants the Survivor an automatic second chance at freedom but also stuns the Killer for a critical 4 seconds. In a game that is built around tension and strategic hunting, this sudden and uncontrollable stun is often perceived as an unfair advantage for the Survivor. It places the Killer in a vulnerable position, effectively undoing all the work and effort they put into downing the Survivor, and interrupts the flow of the chase. This becomes particularly frustrating for Killers who rely on momentum and consistency to win the trial.

Additionally, Decisive Strike causes the Survivor to become the next Obsession, which increases their likelihood of being the Killer’s primary target. While this does add a layer of complexity to the perk, it doesn't mitigate the frustration of being stunned for 4 seconds without the Killer having any meaningful counterplay. The Survivor can remain unhindered while the Killer struggles to regain control of the situation, making it a high-risk, low-reward scenario for the Killer.

In conclusion, Decisive Strike is seen by many as an unfair perk due to its ability to negate the Killer’s efforts without offering any clear counterplay. While its inclusion in the game adds a layer of tension and excitement for Survivors, it creates an imbalance that undermines the Killer’s role in the trial, making it a source of frustration and perceived unfairness within the Dead by Daylight community.