The Legion Dungeons section is wrong...CoS, Arc, and Kara have been available at heroic for a while, and you’re missing CoEN and SotT.
Quickest way to get Cache de trésors antoréens is to do Mythic Maw of Souls x 4. At the end of the dungeon when you defeat the last boss, there's a portal that sends you to the exit. Leave the dungeon, reset instance and zone back in.You will not get any drops from bosses after first run but completing it will still count for quest credit.And before more people start correcting some of the outdated stuff written above in the article, save yourselves time and just remember copy / paste from months old articles and not fixing the changes is still a thing here on wowhead :+))
You don't get extra items from M+ caches do you? From sign of the warrior?
That Fire Relic almost made me confused, was about to pinpoint the specializations that can use Fel Relics instead, because of the 'Fel' in its name. Maybe you could make it bolder (type). That is ofcourse, before you log into the game to double check it :P