Pokémon Mystery Dungeon: Blue Rescue Team Playthrough Part 20 (EXTRA #14 - Purity Forest!)
In this video, we tackle our final 99-floor level restricted dungeon, Purity Forest! This is considered by many to be the hardest dungeon in the entire game. You can't bring any items into it like Wish Cave and Joyous Tower, you're once again reduced to Lv 1, and Reviver Seeds are VERY scarce. Despite these obstacles though, I think it's one of the most enjoyable dungeons.
You need to rely on any items the game gives you if you want to stand a chance here. Kecleon, as you'd expect, is a great pick here because of it having access to nearly every TM on top of tanking most attacks. Frustration, Facade, and Thunderbolt are all useful TMs to find here. It's a really fun and fair challenge... then 80F shows up.
Parasect.
From 80F onwards, Parasect will absolutely rip you apart if you try to fight it head-on without a Pass Scarf. It can put you to sleep or paralyze you, along with hitting REALLY hard with Slash. If you managed to get a Warp Scarf prior to these floors, you'll pretty much trivialize the difficulty of them. If you plan to fight the Parasect though, definitely use a move like Heat Wave or Flamethrower.
Other nasty surprises are Venomoth (Silver Wind) and Electrode (Sonicboom). Thankfully, Venomoth is weak to Psybeam and again, Flamethrower, while Electrode has really bad defenses and only appears on a few floors during the halfway point.