EDNA follows a very strict pattern around a 48-seconds cycle. It will cast 2 combos per cycle before resetting with Earth Shatterer. The combos consist of the following:

• Spawn Volatile Spikes
• 6 seconds later, shoot Refracting Beam on each party member 1 by 1.
• 6 seconds after the last beam, Seismic Smash on the tank

There are 20 seconds between each combo. The main difficulty is to handle the damage from Volatile Explosion. You will have to decide with your team the best way to break the pillars. Each pillar destroyed gives a stack of the explosion. Given the spiky nature of our healing cooldowns, you will want to handle the maximum number of pillars at once, rather than spreading the explosions. You can for example clean 1 or 2 pillars with the Refracting Beams and let Earth Shatterer clear the rest. If you can handle the higher burst, this will make it very easy to know when to use your resources.

There is also an interesting tank mechanic on this boss. Seismic Smash leaves behind Seismic Reverberation. Dispel it to create a Stone Shield on the tank. The best way to handle this is to leave the debuff from combo 1 on the tank until the next Seismic Smash from combo 2. Dispel the debuff right before it to help your tank a ton.

Skarmorak works around Fortified Shell. It will cast it once it reaches 0 energy, replenishing its energy to 100 and creating the shield . Once you break it, it will start spending its energy again, and it will take 47 seconds until the next Fortified Shell is up and running. Add to this the time to break the shield, and you can plan for a 50-55 seconds loop on this fight to plan your cooldowns. It could get to a 1-min loop as keys ramp up, which a lot of healers would love for their cooldowns management, but it is probably better to consider this to be unreliable.

Outside of the Fortified Shell, Skarmorak will cast its combo twice:

• Crystalline Smash is a Tank Buster that will also spawn 3 Crystal Shard
• Unstable Crash is an AOE around the boss that will also spawn 5 Unstable Fragments

The Crystal Shard should be killed one by one, as they explode on death with Crystalline Eruption and leave a debuff that amplify the next explosion (it might be a private aura?). Everybody should collect 1 Unstable Fragments from each wave to have 2 when the shield starts (especially you for the healing amp!)

Crystalline Eruption can add a lot of stress with movement etc, but you should take it slow, focus on good maintenance healing, and use cooldowns if necessary, as long as you keep something for the next Fortified Shell. I would probably go in with a plan for the shells, and then use what's left on the eruptions.