Borderlands 4: One Slimy Issue Walkthrough

Talk to Beth at Lakeside Properties. She'll explain that her basement has been infested with creeps and the surveillance systems are down.

Head to Beth's basement down the steps of the pier. You'll find the door is armored and inaccessible through normal means.

Armored basement door

Locust canister dispenser in mud

Look around the heaps of mud near the basement entrance to find a half-submerged Locust gas dispenser. Grab a canister and throw it at the door to melt through the armor and gain entry.

Once inside, you'll need to clear out the creeps that have infested the basement. These are fast-moving enemies that attack in groups, so area-of-effect weapons work well here.

After eliminating the threats, you'll need to reboot the surveillance system by flipping two switches located in different parts of the basement.

The first switch is accessible by a ladder but is covered in corrosive slime. Grab a Locust canister from a side room and throw it at the console to clear away the growth.

First console accessible by ladder

Second console across from dispenser

The second console is in a small room across from where the dispenser is located. Use another canister to clear this console as well.

Head to the marked location to investigate the monitoring device. You'll discover that a crucial part is missing from the device.

Monitoring device with missing component

Follow the objective on your map to locate the signal of the missing device part, which leads to a nearby ripper camp.

Eliminate the rippers and their leader, the Scrapvenger, who has stolen the device part. The Scrapvenger is a larger, more powerful ripper with increased health and damage.

Retrieve the missing part from Scrapvenger

After defeating the Scrapvenger, retrieve the missing device part from its remains.

Return to the monitoring device and repair it with the retrieved part. Immediately after doing so, a group of threshers will emerge from the ground around the device.

Threshers ambush after device repair

Defeat all the threshers to proceed. These enemies can burrow and reappear elsewhere, so stay mobile during this fight.

Acquire the spare part from the crane near the monitoring device. You'll need to use your grappling hook to reach the crate containing the part.

Use grappling hook to reach the crate

Climb up using your grappling hook and retrieve the spare part from the crate.

Follow the objective to the second monitoring device just ahead. You'll find it covered in biological growth that needs to be cleared.

Shoot the growth around the device

Destroy the growth around the device by shooting it until it clears. Then, insert the spare part to complete the repairs.

Follow the next objective marker to an open muddy area where you'll encounter the Bio-Thresher Omega, a massive mutated thresher that serves as the mission's boss.

The Bio-Thresher Omega has armored skin that makes it highly resistant to damage. Use Locust canisters from nearby dispensers to dissolve its armor before attacking.

Bio-Thresher Omega boss enemy

Strategy: The boss has several attacks including projectile spikes, ground slams, and a charge attack. Stay mobile and use cover when available. When its armor is dissolved, focus fire on its weak spots for maximum damage.

Repeat the process of using Locust canisters to remove its armor and then attacking until the Bio-Thresher Omega is defeated.

After defeating the Bio-Thresher Omega, a vomit pile will remain. Shoot or strike this pile to reveal Beth's pet creep, Colonel Oatmeal, who emerges non-hostile.

Colonel Oatmeal emerges from vomit pile

Colonel Oatmeal will follow you once freed from the pile.

Return to Beth with Colonel Oatmeal to complete the mission. Beth will be grateful for the return of her pet and reward you for your efforts.