Undead Basement in Red Dead Redemption 2

You will need to go there across from Sisika penitentiary.

Grab a boat or steal one (triangle button).

After that, mark a spot on the map and go there by boat.

You have to find a safe spot to go on land.

And use the dynamite to quickly kill guards.

Option->settings->triangle.

After that, turn on the infinite ammunition.

Activate the decrease wanted level.

And then activate set health, stamina and dead eye bars to full.

To prevent guards from spawning, you have to activate decrease wanted level multiple times.

After that, activate create wagon.

Reverse R1 wagon up ramp.

Then climb on the wagon and run up structure.

Some spawned wagons won't work.

Here is another wagon that will work.

Make sure you are here for the next step.

You have to place dynamite here R2.

Drink health potion.

Start dynamite (triangle) and go to bricks.

If you ragdoll on bricks, successful.

You are inside.

Now you have to walk around the roof of Sisika penitentiary.

Go to the center spire.

And remember to lower wanted after each kill.

After that, Go down to the basement level.

Here is the secret undead door.

Arthur turns into undead next to the door.

Go back to the first floor and go out.

Examine prisoners' buildings.

And then examine the guards building.

Examine hanging area.

After that, you have to examine the toilet.

Examine supply entrance area.

Examine fuel stores.

Examine manager residence.