"What this means for speedrunning: start a new game in level 7 or 27, wait a couple hours, go aggro the boss and ensure it cloaks and teleports, then save that game."

You DONT wanna save when your trying to rack up time for the boss to not teleport in the future. You wanna back out of the Level 7 after you've been there for awhile then re-enter Level 7 then Save.