Hey, Twins - It can be done in vanilla mode.

- SPOILER -
Once you're on the other side of the gate at the prison you can fire through the bars
at him. (Thanks to Cap'n Saccade for the info.)

I used the Redux mod - which has a better jump height and leap distance, as well as
being able to climb steeper incline to get on the rocks outside the wall and fired a few
grenades in his general direction.

There's a lot more unique info in my guide if you're interested - that you won't find
anywhere else:

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2429429718

- Thanks for the wave - 8 )