https://docs.google.com/document/d/1zitqE3n8Uh0qxCpQ0lK94v3BTOA7v0BuqH0p_5lLkcw/edit?usp=sharing

This route is a refinement of the original Mural Belt route, with huge optimization of the Kelolon grind as well as several big additions:

1. Silver Necklace A fluke discovery during routing. The Wandering Wrath isn't actually "guarding" the chest, and as a result we can grab this much better accessory for Icefire Wolf Ghost. Contributes to removing the gold cost and time spent buying/equipping Copper accessories, and by extension a number of early-game chests and removing the importance of Dinoram's gold drop.

2. Magic Crystal Ring Originally discovered to be worthwhile by Tute to skip the Lal Mountains Camp, which was the catalyst of all this rerouting. It takes ~1m2s to grab and skips the Forest Camp (~40s+) due to no longer needing Silver Rings. Contributes to the gold and time save of removing Copper accessories, enables a faster 1 Water cast strat for Icefire Wolf Ghost, and makes Jiro much safer in both Wolf Ghost and Silent Ku with the Mega HP Up Elixir we get alongside it. The Black Magic Heart is also very welcome, saves time/medals going into Primitive Cube.

3. Kelolon Grind optimization New medal pickups for a 13th Support Magic Heart, as well as new SP pickups and using the Black Belt to double some of them, has enabled the Kelolon grind to be done in a single visit with 2 less multi-fights overall. Saves at least ~5m, but could be as much as 6m depending on just how much time the new medal and SP pickups take.

4. Removing Bellybutton Ring of Fire Using a combination of the Fire Necklace, Stone Shoes, and Shell Earring on Zola (costs ~16s to grab Shell Earring, saves ~7s from removing Crystal Earring), we're able to skip attempting the 5% steal on Kirin, or the much more likely 1m30s walk of shame to get the Bellybutton Ring of Fire in the Ancient Caverns.

5. Removing Ancient Forest In the original MB route, we spent ~2m50s getting element resist accessories in Ancient Ruins - Forest. Originally in this "Plus" route, we doubled down on the visit and increased it to ~4m50s, allowing us to kill Land Shark C, giving us the Magic Life-Crusher Bracelet and x50 medals for our trouble. Shortly after finishing the route and doing a run of it, I realized that Marumaro survived without fire resistance, and that the Shell Badge exists. Jiro can also survive Heat Press with some HP accessory strats, and Kluke can survive Fire & Brimstone by defending turn 1. Combine that with realizing the Mirror Ring (a ~25s pickup) has either a 2% or 4% chance to insta-kill Mechataclysm and Sneezing Cyclops, instead of relying on the ~20% chance from the Crusher Bracelet, and the entire Ancient Forest visit was removed. Removing it means that at worst this route is ~30s slower than the best luck with the Crusher Bracelet, and over 3m faster than it with quick insta-kills on both bosses with the Mirror Ring. Higher and more consistent floor, much less likely but much higher ceiling. For the sake of differentiating them, probably best to refer to the beta version of this route that fights Land Shark C as Mural Belt "Minus".

6. Magic Attack Up (MAU) A shocking discovery which only happened by chance when looking into the save loading glitch. Turns out this spell isn't behind a black barrier after all, which is the single reason it took this long to be found, as the official guide at one point mislabels it and a Ballet Shoes chest. Not the game-breaking speed boost I thought it might be, but it costs 1m25s to grab and saves ~2m30s throughout all the fights it's useful in (Pyro Dragon, Ultimate Szabo, Nene + Ultimate Nene, Destroy), makes them all much safer, especially in the case of Ultimate Nene with the Marble stalling strats.

I can't say if sub 5 hours is doable RTA with this route, but it seems to be extremely close if it's not. Barring any huge discoveries, this is likely to be the last major reroute, though I wouldn't mind being wrong about that.