With Legion Remix making Legion content current again, it’s much easier and more convenient to get the dungeon and raid meta achievements, 
Glory of the Legion Raider and 
Glory of the Legion Hero.
At max level you’ll one-shot most mobs and bosses on retail because it’s Legacy content. Some of the achievements however require you to do specific mechanics, kite mobs or get bosses into enrage phases. This means you may need to remove gear, change talents, or use special toys or potions. Remix makes these achievements easier since you won’t accidentally one-shot something important. It’s easier to get bosses into enrage, without worrying as much about talents and gear. We’ll highlight a few examples below, but there’s certainly more than just the ones here.
Achievements such as 
You’re Just Making It WORSE! and 
Burning Down the House require you to slowly DPS the boss to be able to trigger what is required for both achievements. There’s a conversation that takes place between Millhouse and Millificent once she reaches 50% in the first one (unless you have the 
Manastorm’s Duplicator), and Shade of Xavius has to reach enrage to make puddles start spawning for the second. 
I Got What You Mead is another achievement made easier on Remix, because you’ll have to kite some mobs around to grab Mug of Mead for all of the kings. You must be on Mythic to complete the achievements, but M+ will work if you start overpower M0.
As you get stronger, you will be able to eventually solo raids in Remix and you can use this opportunity to target some specific achievements. 
I Attack the Darkness, 
Burning Bridges, and 
Elementalry! are three achievements where you’ll have to get the boss to certain HP thresholds, and the last achievement also requires you to kite an add. If you start to overpowering normal raids, the achievements can also be completed on Heroic and Mythic raids as well.
Happy achievement hunting!
