Flub Fuels Scrub Pens is the 21st Level in Munch's Oddysee. Having entered Flub Fuels, Abe and Munch start high up above water, in front of a closed well. Munch can drop down into the water below and pull a lever to open it for Abe, which'll take him nearby to where Munch pulled the lever. As Abe progresses, he'll come across a Lone Slig, which he can possess to use a Voice Lock to open a door leading to a room filled with Sligs to be taken out. It would in addition be a good idea to take out the Sligs surrounding the drained water with lots of Land Mines down below, so that Abe can cross safely. As Abe crosses, he'll come across a lever to open up a door for Munch to come through into where he is, but Abe will first need to raise the water back up so he can get through. Before pulling the lever that does so, it would be an idea to save the Scrubs in the surrounding pens (all of them also have nearby Bird Portals) first, since raising the water will also drown any Scrubs that haven't been saved. Once the water is raised, Munch can hop onto a platform to pull a lever that'll open a door for Abe to a room with a SoBe/Health Up Vendo on the other side, as well as another Resurrection Egg. There, Abe will need to jump across the water on platforms, and reach an area high up with Scrubs on alcoves with nearby Bird Portals, as well as a Corridor with Caged Fuzzles that Munch will need to save. Then once the nearby door has been opened, the duo will come across 2 Big-Bro Sligs, that can be taken out by having them either take on each other through Abe's possession, or by having Abe possess a nearby Slig to take them out, sending the Fuzzles to take them out wouldn't be such a good idea seeing how Tough those Enemies are. Once they're taken out, there'll be a Floor Switch to open up a door with the Exit Pads that'll drop pretty fast, but thankfully there's a nearby Expresso to help the duo get over there fast enough before the door closes.
- Fuzzles appear for the first time since The Mudokon Fortress, being like this one of only the 3 Non-Vykker's Labs Levels to have them.
- This is the only level to have a Floor Switch that'll hold a door open permanently, since the Floor Switch at the start of the level never does drop when walked off.
- This is the last level to feature Mines, both Land and Water.
- This is the last level to have Sligs, but not the last level to have Big-Bro Sligs.