Hey Maxime, currently no functioning autosplit is available for D2R, so manual splitting is the only option.
Kasya, it is something that can happen. If he laughs but you don't get the skip that typically means you didn't properly cross the line, didn't go deep enough into the throne room on your turn around(or way early - you have ~0.5-0.8 seconds leeway on when you go back in). If he did not laugh and you missed the skip that means you went too deep on your reentry. It's hard to put into words but does that make sense? Also Delusional I presume you meant seconds cause his laugh is definitely not 6 frames (~0.25 seconds) long.
I mean a way to do it now would be to provide players with a seed say 2 minutes before a run. They create a character with that seed and then turn off -seed. Could be interesting to do the run seeded too tbh.
I'll sum up the ancients trick because I know there are others who can go way more in depth on wave skips than I can. Bugging ancients to create impassable terrain is done by opening a town portal when korlic leap attacks. The game "saves" Korlic's landing location and makes it impassable. Repeating this you can create large impassable areas on the arreat summit, most commonly used midway up the right side to create a "wall" between the pillar and edge of the arreat summit. This wall can still be passed by Talic with WW and Korlic with Leap attack if you get too close. If you go to town after setting up this wall sometimes it can "despawn". Using ranged skills you can "cheese" the ancients, normally only worth it on Hell difficulty. The most commonly used classes for this are Zon (Immolation arrow), Sorc (Blizz/Hydra/firewall), & Sin (traps). Necro could use this with bone skills however I am not up to date on Necro strats and believe they do edge with summons instead.
1-25 would be jail grind then smash through a2 to get to flayer jangle.
26-45... hmm likely depends on the class but I can see nm flayer leveling or nm tower/pit or something. Cause Pindle and eldritch would fall off hard around level 37.
I can see 1-80 runs being a thing, I also don't mind them being rolled in 100% Hell runs by making it so you need to be level 80 to finish.
The only thing I would say is maybe provide a link/information to example shared stashes (the github or something) and put that in the category rules for ng+. Want to make it as easy to access as possible.
Australia

