This is mainly for new people who want to speedrun the game but don't want to fight the final boss normally or aren't good with PK and clipping Silhouette out of the bounds of the arena

Silhouette is able to be killed by shooting her with 21 fully charged Anal Probe shots. This will bypass her regeneration abilities completely and she'll die like any other NPC hit with enough successful probes.

Upon landing at The Octagon take out and use the Ion Detonator on the robots over the gate in front of Silhouette. Once those are down switch to the Anal Probe and charge it before hitting her the first chance given. Repeat charging while stepping back to keep her from attacking and getting close to her when the probe is mostly charged.

While doing this it is best to lead her to the right side of the arena where no debris and no Majestic Agents are located. Doing so leads to a flat plane with only a Psi-mutant and an EMP on the far end. Clear any enemies as you see needed. If done effectively the fight will last about 2 minutes

I have put a video of me showing this quick kill strategy below for those who want it.