Mt. Targon Base

The base of the legendary Mount Targon. This is where many begin their ascent; some do it for enlightenment, others to prove their self-worth and others for reasons involving celestial deities. But for Aatrox and Boris, this is where they have their final showdown against each other, an all-out duel to the death. No retreat, no mercy and no one else to interfere.

Map
Mt. Targon Base is an extremely wide rocky arena with a few climbs in terrain with a gray sky above, but is otherwise a relatively flat area. No walls or obstacles are here outside at the outer edges of the map, serving as the border for the arena. Due to this, terrain advantage is situational save for at a few parts of the map, where the escalation in terrain can prove useful against Boris especially during his third phase.

Upon entering the map, the player is spawned close to the edge of one of the walls, where Boris stands alone in the middle. Approaching him will trigger a cutscene and the fight against his boss version.

Boris Boss Fight
"To war, Aatrox! They shall not rob us of our nobility! We shall stand, and spit venom at our tormentors for eternity!"

Boris will permanently be in his True World Ender state, and unlike the player character, this Boris is a powered up version and has features exclusive to him including the following; Boris attacks will be strengthened and change based on the phase he is in and all are extremely hard-hitting attacks. Additionally, most of them, especially in his second and third phase, are unable to be parried and require dodging away from his attacks instead.
 * Boris ' True World Ender Form does not grant him Health Regeneration, and Boris has no methods of recovering health, ensuring that every bit of damage you do against him counts. However, in return, bringing him down to a certain health threshold will cause him to enter another phase with extra attacks exclusive to this fight only.
 * This form does not alter Boris ' voice whatsoever, and will remain the same as his default voice.
 * Boris makes use of most of his other abilities, but not all such as Dark Flight and Umbral Strike, playing very similarly to his League counterpart minus with the previously established changes earlier.

First Phase
"Fight! Or be forgotten!"

The easiest phase against Boris, he possesses very few attacks which aren't particularly deadly. Fighting Boris here is simple to the point just wailing on him mindlessly is fine.
 * Sword Swings - Boris swings his sword horizontally, dealing a fair amount of damage to the player. These attacks can be parried.
 * Executioner's Calling (Downward Cut/Q1) - Boris raises his sword and lets out a downward slash, if this connects it will deal a good amount of damage. Can only be dodged.

Second Phase
"Your annihilation beckons!"

Bringing Boris to roughly 75% of his Health will trigger his second phase, where he will gain access to the entirety of his Darkin Blade combo, while lighting falls from the sky to damage the player. On top of his attacks from above, he gains new attacks and has a 10% increase in Attack Speed. However, to compensate, Boris will always attack in a set order making him predictable for the player.
 * Thunderlord's Decree - Lightning will occasionally drop from the sky. If this hits the player, the player will take minimal amount of damage. Though this does not interrupt Boris or the player, effectively making this ability mostly for dramatic purposes, as even the accuracy of this attack is abysmal.
 * Sword Swings - Though the same as above, Boris will unleash this faster. This will always lead to Q1.
 * Executioner's Calling (Downward Cut/Q1) - Boris raises his sword and lets out a downward slash, this time preparing to let out a full combo. If this connects it will deal a good amount of damage and can only be dodged.
 * Army Cleaver (Horizontal Sweep/Q2) - Boris cleaves in the shape of a cone in front of him, dealing more damage than the Q1. Only follows after the said attack. Can only be dodged.
 * Dark Impact (Sword Slam/Q3) - Boris soars high up into the air before crashing on the ground. Can only be dodged, should this hit a significant amount of damage will be dealt.

Third Phase
"Carnage... Hate...! Yes! I am the World Ender!"

When Boris reaches approximately 40% Health, his full wrath will be unleashed: with enhanced attacks, more frequent strikes and lightning on top of being a lot more mobile accompanied with even more of his attacks being used. Upon entering this final phase, Boris receives a total of 20% increase in Attack Speed and additionally gains 10% Damage Reduction. Additionally, Boris loses all form of predictability and will instead more or less randomly pick which attacks to use, including which version of his Qs, meaning he can use Dark Impact directly.

Boris gains new deadly attacks while in this phase also, these attacks also have the potential to kill in one-hit or combo, so be extra careful as one mistake can cause you to lose the fight in a second. Should you find yourself triumphant over Boris, you will gain access to new stages and unlock Boris.
 * Crimson Torrent (Energy Orbs) - Boris channels for a moment to gather energy, before expending out energy around him and unleashing several red airborne orbs to chase down the player. Though the orbs aren't extremely fast, they are fast enough where you can only evade them through use of the terrain taking advantage of their tracking, or dodging repeatedly until they all collide with the ground. Boris immediately uses this attack upon entering this phase and periodically uses it again, it is heavily advised to leave his vicinity as the initial energy burst he lets out will instantly kill you.
 * Deathbringer (Dashing Stab) - Boris dashes an incredible distance while stabbing, a multi-hitting attack that does an incredible amount of damage, it is highly advised to dodge horizontally.
 * God Killer (Dashing Downward Cut) - Boris prepares a strike similar to Executioner's Calling, however Boris additionally dashes towards the player even from afar, and is an entirely different attack.

Aftermath
"I have bent the realm of the dead to my will. This world shall be next."

After Boris is defeated, Mordekaiser will appear. He is extremely durable and powerful. After you bring Mordekaiser down to 50% Health, he will activate '''Indestructible. Indestructible gives him even more Armor instead of healing in this fight and it also lasts for approximately 100 hours''' in this fight. You are meant to lose this fight. You are transported to the Realm of Death when you take fatal damage.

If you defeat Mordekaiser, he will drop Nightfall, one of the strongest Weapons in the game.