Gladius' Everdark Sovereign fight features a brand-new white look for the boss, and upgrades some of its regular attacks while gaining new ones, increasing the difficulty of the fight.
The boss will start the fight in its second phase, split into three separate dogs, which keep the regular moveset. Gladius constantly howls, making the other dogs focus a specific party member. While being focused (you will see a dark circle on your character), focus on running away and dodging while your teammates attack the dogs.
Around 70% HP, the three dogs will merge and transition into the Everdark phase, gaining a new set of attacks and increasing the range of other regular ones.
Some of Everdark Gladius' attacks cover a wide range and leave lingering AoE damage, so having access to extra healing, flasks, and HP boosts will greatly aid during the fight.
Gladius is weak to holy damage, and dealing enough Holy damage will stagger it, and decrease its attack and defense for a certain time.
Everdark Phase - Phase Three
When Gladius falls below 70% HP, it will enter its Everdark phase. You can freely hit the boss during this time. Immediately after, it will perform two quick lunges and then create three sets of fissures on the ground, very similarly to Heolstor's ultimate move.
Gladius can lunge and bite at nearby players just like its regular version, and also swing its sword in 360-degree sweeps around. His melee moveset is relatively similar, and players will find it easy to dodge its attacks if they can maneuver around its body.
Triple Fire Wave
Gladius will run away from players, set its mouth and sword ablaze, and shoot three fire waves at players. These cover a wide range and area to the sides, so dodging in the exact timing is crucial to avoid damage.
Extended Sword Combo
Gladius' sword combos create fire explosions, and it has a new follow-up move. It will start with two downward slams at players, then a 360-degree sweep, and a final horizontal lunge. Dodge the first one sideways, run away from the second one, get away from it to avoid the third hit, and dodge or run in any direction to not get hit by the final one.
These moves have a higher hitbox than the usual sword attacks due to the fire explosions, so don't hesitate to move away further than usual to avoid getting hit.
Phase Four
After Everdark Gladius is brought below 40% HP, it will split into three dogs again. This time around, it will perform a dangerous phase transition attack, where the dogs will lunge at players with incredible speed multiple times, ending with a howl and a last lunge that triggers an explosion afterward.
This attack is practically impossible to dodge unless you know the exact timing, so dodge a split second after the dogs are ready to lunge, and dodge twice in quick succession to avoid the final lunge. Running perpendicularly to Gladius is another viable strategy to dodge, but avoid running toward other players. You could also save your ultimate and use its invincibility frames to dodge the attack.
In phase four, the dogs become more aggressive, attacking nonstop. The target mechanic is back, and the player who has been targeted by Gladius (indicated by a dark red circle over the character) should avoid attacking and focus on dodging and running away.
The main dog will always use the sword, performing quick slashes, while the others will lunge and bite players, focusing on the targeted Nightfarer. Gladius will target players two or three times before merging again into a single dog, reverting to Phase 3. If this phase seems difficult to deal with, you could always stall it out, running away from the boss until it reverts.