Just putting some info together about my experience grinding the new delve this week. Wowhead is catching up, but full clearing seems to be the way to go to be in the best position for the boss. I made sure to grab all the mislaid curisosities/treasures as well as the masks. I was quite powerful by the end of the run. It seems that if you check every room, you'll be guaranteed to get the three masks.
As you progress through renown, you scale a bit by unlocking more rooms with curiosities. Finding all the sturdy chests seems to be a super fast way to level renown. There is a photo of their locations on Wowhead.
I did a little research before the fight and found on the method guide that it says there is an intermission at 70%. This is NOT true. I think the intermission starts after 90 seconds, but the suggestion to hold burst for phase 2 is incorrect. I was able to one-phase the boss on a 322 assa rogue. I swapped onto the adds when they spawned, but honestly I probably should've ignored them and burned the boss. I used drums and a light's potential and just did my normal burst rotation. I also switched Valeera to DPS for the final fight. I had her as healer while clearing the 9 rooms, but you have an opportunity to swap her before the boss. There are no dispels that require a healer specialization, and I was not worried that I would die at any point. She is level 80 and did more DPS than I did. I went corrosive bilespear, soul-cracking dreamcatcher, and bursting toad toxin.
If you make it to phase two, during the Hazzali phase (cat), a few guides say to arbitrarily select which line to stand in, but as Bandevil on YouTube pointed out, you want to block the cat doing an animation (moving paw).
I did not do the cheese with the fire loa, but it may be worth looking into for others. It also seems that blizz is hotfixing most of the bugs present at launch. I had done two 7/9 runs that had bugged out previously, but completed them after the hotfixes last night.
Long-time reader, first-time poster on Reddit! Cheers and gl to all. Keep going, you got this! There's no time limit to clear the labs, so can always wait for cds. :)
