How does the throne room glitch work to skip waves + how does town portal trick work to bug ancients in that spot?

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.