Glory of the Legion Hero at 120(+)

Now that we're up to into BFA and have a gear score over 370, going back to solo Legion dungeons is rather painless. With 10 levels, your toon can walk passed most trash mobs and quickly take down those that you need to engage. The achievement Glory of the Legion Hero has 26 meta achievements. Several of those you may have already completed as you played through the area. I found that I completed about half of them already on either my paladin or hunter toons. Since the achievements are account bound, you can complete them in any order, on any toon. There are 3 achievements that you'll need 5 people.

Eye of Azshara

• But You Say He's Just a Friend - burn down boss, don't kill trash. don't have boss spear shellbreakers.
• Stay Salty - boss summons droplet adds. do nothing to adds until 10 are there. boss puts debuff on you that expires in a focused spray. Use that spray to kill 10 droplets at the same time.  The problem I had is boss only calls player # * 2 of droplets. So if trying to solo, you have to not kill any droplets for 5 waves of adds. Having more players in the dungeon would make this go faster!
• Ready for Raiding V - avoid bosses abilities. 

Darkheart Thicket

• Burning Down the House - pull boss to 5-15% health, stop all dps. kite him through voidzones until he has 10 stacks, kill boss. 
• Egg-cellent! - Egg behind Dresaron. Open it before starting boss fight.

Neltharion's Lair

• Can't Eat Just One - let boss eat 4 adds and will probably eat you two times, have healing pot or healthstone.
• Got to Ketchum All - yeah pokemon. Need to squish 7 snails in dungeon using a ketchum tablet bought in dungeon. 2 snails need something to get them near you. My warlock was able to fear or shadowfury them both. This caused them to move. DON'T KILL SNAILS before you smash 'em with tablet.

Halls of Valor

• I Got What You Mead - need at least 4 people. Kill first 3 bosses to open up path to Odyn's area. 4 people each grab a jug of mead off tables. Splash the four bosses simultaneously. 
• Surge Protector - burn down the boss before adds cast Surge
• Stag Party - 

Assualt on Violet Hold

• I Made a Food!
• You're Just Making It WORSE! - /tease millificent manastorm when prompted in fight. Helps if you have the manastorm replicator.

Vault of the Wardens

• I Ain't Even Cold - when boss casts a line of lava pools, run through all of them to get debuff. kill boss while debuff active.
• A Specter, Illuminated - two specters are only visible using the light of elune. Need to carry it back the elevator to find them. (click on title for detailed comment)
• Who's Afraid of the Dark? - burn her down to 45%, she'll cast creeping doom. run through the gates, pick up orb to find and kill add, finish off the boss. 

Black Rook Hold

• Black Rook Moan - Looks like you can get boss to 50% health, it summons adds, then drop boss below 15% and adds don't despawn. Wait for them to convert to a frustrated soul. Kill the add, then kill the boss.
• You Used to Scrawl Me In Your Fel Tome - read all the hidden books in the dungeon. 
• Adds? More Like Bads - 

Maw of Souls

• Instant Karma - 
• Poor Unfortunate Souls (needs 5 people) - click on font at beginning of BRH, complete dungeon then run Maw of Souls.
• Helheim Hath No Fury - kill the first and second boss quickly.

Arcway

• Clean House - burn down boss or soak all pools he summons.
• Arcanic Cling - burn down boss to avoid his damaging ability.
• No Time to Waste - avoid timeless wraiths as you are running back to the last boss.

Court of Stars

• Waiting for Gerdo - 
• Dropping Some Eaves - don't let anyone trigger the alarms. disable or kill before they can be triggered.