Mithrix

Mithrix is the final boss of the game found in Commencement, the final stage.

Mithrix is the brother of Providence, the final boss of the first game; the two's relationship is detailed throughout many of the game's logs, many from Mithrix's perspective, including those for, A Moment, Fractured, Bulwark's Ambry and more.

Adaptive Armor
During phases 1 and 3 of the fight, Mithrix has the Adaptive Armor passive which protects him against bursts of damage. Every time Mithrix takes damage, he will gain temporary armor equal to 3000 * (damage / maxHP), in other words, 30 armor per % of his max HP dealt. This temporary armor caps at 400 and decays at a rate of 40/s.

Phase 1
Mithrix will start by doing his basic attacks, which consist of running around, dashing while swiping with his hammer for 200% damage, smashing the ground with his hammer causing an explosion for 1200% damage (with damage falloff) and an additional 1200% damage on a direct hit (the hitbox is fairly small), and running at the player while firing up to 12 needles for 60% damage each. His more advanced attack is jumping into air of the center of the stage and slamming down, causing a 360 shock-wave around the stage which deals 400% damage. The wave ends when it reaches the thin line made of rocks between the platform where he is first seen and the outer platform with a small slope.

Phase 2
Terrain changes (several stone pillars rise up) and several Lunar Chimera Golems and Lunar Chimera Wisps are summoned which must be defeated. Mithrix is not present during this phase while new chimeras are occasionally summoned.

Phase 3
Mithrix comes back with more powerful and different attacks, occasionally summoning Lunar Chimera Golems and, more rarely, Lunar Chimera Wisps. His moveset is similar to the first phase but the attacks have additional effects to them. He also gets more aggressive and attacks more often. His slam leaves a lingering pillar of flames that deals 150% damage per tick and sends 3 small, directional shockwaves similar to the shockwaves from groundpound attack, dealing 200% damage and applying the cripple debuff. Mithrix also gains an additional attack, in which he will summon moving lines of flame that spin around him and explode after short delay, dealing 900% damage and applying cripple. This attack is repeated 4 times.

Phase 4
Mithrix steals all players' items and gains their buffs. Hitting him gives some items back (notably in reverse order). He will fire a burst of projectiles similar to those fired by using Visions of Heresy, slowly stomping around the battlefield. He will also occasionally kneel and fire fast travelling orbs for 400% in eight directions, simultaneously dealing 8% of his current health in damage to himself.

Aftermath
Once Mithrix is defeated all taken items are returned, the Moon will begin a detonation sequence with an on-screen countdown. A shuttle will fly in along with a pair of TC-280 drones, and the surviving players have 4 minutes to get to the shuttle in order to escape. Sporadically, lines of flames will appear, similar to the columns used by some of Mithrix' attacks. Void Reavers will also spawn and attack the player.

Successfully making it to the shuttle will complete the Washed Away challenge and unlock the Captain as a playable Survivor, and, on Monsoon difficulty, will complete the The Calm challenge and unlock.

Tips

 * Mithrix cannot climb the pillars that appear on the phase 2, so if you manage to climb them and do only ranged attacks, the third and fourth phases will be very easy. The ranged attack on phases 3 and 4 can be easily dodged from higher ground too.
 * Mithrix will take but not use any, , or  during phase 4.
 * Mithrix will not take during phase 4.
 * Mithrix will take and use the Captain's during phase 4.
 * Mithrix will take and use during phase 4, making the fight significantly harder until they are recovered.
 * Mithrix will take and use during phase 4. However, you will regain an unspent Dio's Best Friend along with all other stolen items upon Mithrix's first death. If you take it back before he dies, he won't gain a second life.
 * Hitting Mithrix during phase 4 will return items in the order they were taken, and will return an entire stack at once.
 * Artificer's Snapfreeze and Cast Nano-Spear skills are capable of freezing Mithrix, unlike other bosses.
 * Stacking is another easy way to kill Mithrix, as he will get the reduced hp effect as well. Making bursting him down very easy.
 * When using, two Mithrix will spawn. Players must kill both bosses before they will advance from one phase to the next. However, when one's health is emptied, it will be incapacitated until the next phase.
 * Mithrix, like other Special Bosses, cannot spawn as an Elite, so using the in combination with  is not a valid strategy to kill him quickly.
 * During escape if you have a and enough movement speed or you are playing Artificer, it is possible to fly to the extraction point.
 * Mithrix steals items from minions, like Engineer Turrets. He won’t use the items he takes from minions.
 * During phase 4, only attacks with a Proc Coefficient have a chance to return an item.
 * During phase 4, Mithrix will not use his orb attack while his health is above a certain threshold. As long as he has healing items, players can keep his health high to prevent him from using the orb attack until they get more items back.

Dialogue
Mithrix will also speak during the fight. His lines can be seen in the chat box.

Toggle Dialogue Spawning
 * Pray.
 * Beg.
 * Die.
 * Be slaughtered.

Dealing damage (early phases)
 * Bleed.
 * Now is the time for fear.
 * Weak.
 * Frail - and soft.
 * You are nothing.
 * Mistake.
 * Scream, vermin.
 * Break beneath me.
 * Slow.
 * Your body will shatter.

Dealing damage (late phases)
 * BLEED.
 * SCREAM.
 * WHERE'S YOUR INFLUENCE?
 * FLEETING STRENGTH.
 * FRAIL.
 * BREAK.
 * FALSE STRENGTH.
 * DRAIN.
 * DIE, VERMIN.
 * WEAK, WITHOUT YOUR BAUBLES AND TRINKETS.

Player is killed (early phases)
 * Return to dirt.
 * Submit, vermin.
 * Die, vermin.
 * Die, weakling.
 * Become memories.

Player is killed (late phases)
 * DIE.
 * WEAK.
 * USELESS.
 * AS I THOUGHT...
 * VERMIN.

Mithrix is killed
 * NO... NOT NOW...
 * WHY... WHY NOW...?
 * NO... NO...!
 * BROTHER... HELP ME...!
 * THIS PLANE GROWS DARK... BROTHER... I CANNOT SEE YOU... WHERE ARE YOU...?
 * BROTHER... PERHAPS... WE WILL GET IT RIGHT... NEXT TIME...