Well I finally managed to complete a mythic +15 within the time limit.
https://worldofwarcraft.com/en-us/ch...legion-dungeon

All I needed was a 950 iLvl and about 150 artifact traits to do it.

It was a Neltharion's Lair run with 5 paladin tanks. I had Bolstering, Skittish, and Fortified. Bolstering is not too bad since pali tanks are strong in AoE, skittish has no effect on them whatsoever, and then there is fortified which is the toughest affix I can get because of my low DPS.

https://imgur.com/a/8a6v2Rb