The frustration is understandable, as Eonar is not in-line with other legacy bosses, but the encounter is soloable by any class if you’re willing to sit down and practice a bit. When I started to farm Antorus, it took me around 40 minutes of practicing, after watching a guide, to get the encounter down, but after that I could one-shot the encounter on all my alts, of every class. If you’ll bear with me for a little, I can give the step-by-step on how to do it:
First lesson: do not kill everything on sight. Every time you kill adds, Eonar’s energy bar goes up, and at full she wipes the area. You need to make it so she clear the area right after a new portal spawn and just before you enter the ship. The Fel Reavers are to blame for most wipes as they nuke Eonar soon after they spawn, so they should be your priority targets.
To accomplish this, you’ll do the following: after you start the encounter, jump to the entrance, that’s where the first portal spawns. Kill the first wave of adds until the Fel Reaver spawns. Kill it then jump to the high platform close to Eonar (assuming your character is facing her to start the encounter, the platform is to the right of your character). There will be a single add spawn and a Fel Reaver. After you kill them, jump to the front of Eonar and wait for the add wave to get close and kill it. Then, wait for the add wave to the right of Eonar to the start going up the ramp and kill one of them. This will prompt Eonar’s clear and you can go into the ship asap.
Kill the add on the ship and proceed to the crystals. Make sure to go to the back crystals first. As stated above, once you click the crystal, you can walk while channeling the cast, so click and go to the next one. Use movement ability to cross the hallway to the 3rd crystal then use the wing jump to get to the 4th. You should have plenty of time before the ship’s nuke. After exiting the ship, go immediately to the opposite side of the area, that’s where the next portal will spawn.
The portal will have adds and a Fel Reaver. Kill everything there and jump back to Eonar and await the next add wave to get to her. Kill one of them and she’ll nuke the area again. Now go back to the portal opposite of Eonar’s location.
DO NOT ENTER THE 2ND PORTAL TO THE SHIP
Kill the last wave of adds and Eonar should do a final nuke in the area and end the encounter.
If you’ve done what I described and is still missing a bit for the final nuke, jump to the center platform and wait for the bats to fly by and kill them and you’ll still complete it.
Again, most of the encounter revolves around killing add groups around a set timer. There’s a bit of wiggle room for mistakes, but with practice you’ll be able to do Mythic Eonar with just muscle memory.