"Repliforce are the fools this time! Now, all that's left is to destroy Earth with the very weapon they made!"

—Sigma

Sigma is the final boss of Mega Man X4. While the Maverick Hunters and the Repliforce were busy fighting each other, Sigma took control of the Final Weapon and planned to use it on Earth, forcing X or Zero and the General to stop fighting in order to stop the Final Weapon before it could be used.

Strategy[]

First form[]

Sigma is revealed as the mastermind behind the chaos, and fights against X or Zero himself in his Phantom Sigma form.^[1][2] Initially, Sigma's appearance is hidden by a tattered black and red cloak and now he is armed with a beam scythe, resembling a Grim Reaper. This form can only be damaged by X's Rising Fire or Zero's Ryuenjin. Sigma constantly teleports, using one of two simple attacks. The best moment to attack is as soon as he appears.

	Shot Attack (ショット攻撃, Shotto Kōgeki)[3]
	Sigma releases projectiles which either drop to the floor and spread outwards, or immediately spread out before crossing the floor.
	Damage: 6
	Scythe Attack (鎌攻撃, Kama Kōgeki)[3]
	Every third time Sigma appears, he swipes across the arena with his scythe held below. He is invincible to everything when performing this attack. The player can avoid this attack by staying at the topmost part of the walls.
	Damage: 9

Second form[]

After taking enough damage, Phantom Sigma's cloak is burned off, revealing his uncloaked form.^[1] Although it is technically the same body, Sigma recovers his health and changes his strategy.

Sigma starts by throwing his scythe, once around himself and next so it sticks into a surface and emits electricity. Depending on which surface it struck, he attacks with either boomerangs or laser eyes. He then repeats the pattern. The laser eye attack is slightly easier to dodge and can be taken advantage of by going behind Sigma during the attack, so it's best to bait him into sticking his scythe into the wall to prompt this move. In this form, Sigma is weak to X's Lightning Web and Zero's Rakuhouha.

	Scythe Throw (鎌投げ, Kama Nage)[4]
	Sigma jumps and throws his unlit scythe in a circle around himself.
	Damage: 9
	Laser Attack (レーザー攻撃, Rēzā Kōgeki)[4]
	Sigma throws his scythe directly at the player. The scythe then sticks into the surface it hits, emitting electric charges as long as it stays there.
	Damage: 9 (scythe), 6 (electricity)
	Boomerang Attack (ブーメラン攻撃, Būmeran Kōgeki)[4]
	If Laser Attack charges the floor, Sigma ejects four boomerangs from his shoulders that sequentially chase the player, staying in place midair. They then fly at the player a second time, flying off-screen.
	Damage: 6
	Laser Eye (レーザーアイ, Rēzā Ai)[4]
	If Laser Attack charges a wall, Sigma leaps to the other side of the arena and fires eye lasers diagonally across the floor. He holds the lasers for a long time, but the entire wall behind him is safe.
	Damage: 9

Third form[]

In his final form, Sigma controls multiple bodies. He has two main bodies: Gunner Sigma (シグマガンナー, Gunner Sigma Sigma Gunner in Japan)^[5] and Earth Sigma (アースシグマ, Earth Sigma)^[5], along with three Mini Body (ミニボディ, Mini Body)^[6] drones shaped like his head. He constantly changes forms in this pattern: Mini Bodies, Earth Sigma, Mini Bodies, Gunner Sigma, repeat. Gunner Sigma and Earth Sigma do not share one health bar; if the player destroys one of them, they must contend with the other until that one is destroyed too. The Mini Bodies do not have health meters and merely regenerate after being destroyed.

Mini Bodies[]

The Mini Body (ミニボディ, Mini Body)^[6] drones are three metallic idols resembling Sigma's head, each with an elemental alignment. The red head spits fireballs, the yellow head shoots electricity, and the blue head has ice breath. They can be destroyed, but doing so does not affect Sigma's health, and they regenerate for every cycle. They are weak to X's Charge Shot and Zero's Ryuenjin.

	Flame Shot (炎弾, Honō-dan)[6]
	The red Mini Body spits four sets of fireballs, following the player vertically.
	Damage: 6
	Electromagnetic Shot (電磁弾, Denji-dan)[6]
	The yellow Mini Body fires six spheres from its forehead, which split into electric bolts along surfaces.
	Damage: 6
	Ice Fog (氷霧, Hyōmu)[6]
	The blue Mini Body breathes a cold fog onto the floor as it crosses the arena.
	Damage: 9

Earth Sigma[]

Earth Sigma (アースシグマ, Earth Sigma)^[5], also known as Slime Body (スライムボディ, Slime Body)^[6], is a giant, disfigured head of Sigma. It appears in the bottom left corner of the arena and attacks with its mouth. Its open mouth is its weakpoint. It is weak to X's Ground Hunter and Zero's Shippuuga or Hyouretsuzan.

	Spike Attack (トゲ攻撃, Toge Kōgeki)[6]
	Earth Sigma summons spikes on the right wall, then creates heavy winds to push the player into them. The spikes do not cause instant death, but still deal heavy damage.
	Damage: 24
	Slime Body (スライムボディ, Suraimu Bodi)[6]
	Earth Sigma starts inhaling debris, also pulling in the player to bite them, before spitting the debris back out in a random fashion across the arena.
	Damage: 9 (bite), 6 (debris)

Gunner Sigma[]

Gunner Sigma (シグマガンナー, Gunner Sigma)^[5], also known as Cyborg Body (サイボーグボディ, Cyborg Body)^[6], is a large humanoid robot body with Sigma's face emblazoned on top of its head. Sigma's face is its weakpoint. It appears in the top right corner of the arena and attacks with laser gun. It is weak to X's Soul Body and Zero's Ryuenjin.

	Clear Laser (スライムボディ, Nagiharai Rēzā)[6]
	Gunner Sigma fires a laser beam that sweeps across the whole floor.
	Damage: 9
	Tracking Laser (追尾レーザー, Tsuibi Rēzā)[6]
	Gunner Sigma fires a laser beam in the player's direction. It can only aim at three specific angles, limiting its range.
	Damage: 9

Damage Data Chart[]

X[]

	X-Buster	Lightning Web	Soul Body	Aiming Laser	Double Cyclone	Rising Fire	Frost Tower	Ground Hunter	Twin Slasher	Nova Strike
1st Phase	0:0:0	0:0	0:0	0:0	0:0	6:4+	0:0	0:0	0:0	0
2nd Phase	1:2:3	4:4+	0:1+	0:0	0:0	0:0	0:0	0:0	0:0	6
Earth Sigma	0:0:2	0:0	0:0	0:0	0:0	0:0	0:0	2:3	0:0	4
Gunner Sigma	0:1:2	0:0	3:0	0:0	0:0	0:0	0:0	0:0	0:0	4

Zero[]

	Z-Saber				Special Techniques
	First Slash	Second Slash	Third Slash	Wall Slash	Kuuenzan	Raijingeki	Ryuenjin	Hyouretsuzan	Shippuuga	Rakuhouha
1st Phase	--	--	--	--	0	--	6	0	--	0
2nd Phase	1	1	3	1	3	3	0	2	1	4
Earth Sigma	1	1	2	2	2	0	0	3	2	0
Gunner Sigma	--	--	--	2	3	--	4	2	--	1

Notes[]

• For X-Buster, the first number is damage done with standard, uncharged shots; the second is damage done when the weapon is charged a bit; third number is damage done when it is fully charged.
  • A fully-charged X-Buster shot does the same damage in all of its forms (normal Charge Shot, Stock Shot, and Plasma Shot).
  • Any subsequent damage inflicted after the Plasma Shot's initial blast is 1 unit per hit.

• For the eight Special Weapons, the first number is damage done when the weapon is used in normal fire; the second is when the weapon is used in its charged state.
• For Special Weapons that are capable of striking more than once, damage values on this chart are listed according to how much a weapon inflicts per hit, not the total amount of damage done. Those that do strike more than once will be marked with a plus sign.
• For Soul Body, the first number is damage done with the hologram, and the second number is damage inflicted with the buster shots fired from the solid hologram; the solid hologram itself cannot inflict damage to Sigma.

Dialogue[]

In-battle quotes[]

Action	Japanese	Translation	Audio (JP)	English	Audio (EN)
Pre-battle	地獄に旅立つ準備は出来たかね？(Jigoku ni tabidatsu junbi wa dekita ka ne?)	Are you ready for your journey to Hell?	File:X4 Sigma1 Pre1 JP.ogg	Are you ready for your final journey?	File:X4 Sigma1 Pre1 EN.ogg
Pre-battle	宇宙の塵になるがいい！(Uchū no chiri ni naruga ii!)	Become space dust!	File:X4 Sigma1 Pre2 JP.ogg	Prepare to become space dust!	File:X4 Sigma1 Pre2 EN.ogg
Pre-battle	とびっきりの恐怖を味わってくれたまえ。(Tobi kkiri no kyōfu o ajiwatte kureta mae.)	Have a taste of extraordinary fear.	File:X4 Sigma1 Pre3 JP.ogg	Tremble with terror! You are finished!	File:X4 Sigma1 Pre3 EN.ogg
First form defeated	これで終わりと思うな！(Kore de owari to omou na!)	Don't think this is over!	File:X4 Sigma1 Uncloak JP.ogg	Are you ready for round two?	File:X4 Sigma1 Uncloak EN.ogg
Clear Laser	終わりだ！(Owari da!)	It's over!	File:X4 Sigma2 ClearLaser JP.ogg	The end!	File:X4 Sigma2 ClearLaser EN.ogg

Other appearances[]

Sigma appeared with this body in Project X Zone 2, and this is the form from the Sigma costume in the Dead Rising 3 mode Super Ultra Dead Rising 3' Arcade Remix Hyper Edition EX + α.

Mega Man X DiVE[]

Sigma (X4 1st form), named Phantom Sigma in the game's official site,^[2] appeared as the second Raid Boss in October 2020, with some changes from his Mega Man X4 appearance, combining elements from his second form:

Attacks:

• Sigma swipes his scythe in a straight line. This attack is identical to Mega Man X4.
• After disappearing, Sigma may reappear close to the player to catch and cut his target with the scythe.
  • If the previous attack fails, Sigma throws his scythe on the center of the room. After hitting the ground, it will continuously release laser beams across the surface. While the scythe is on the ground, Sigma will warp and release energy spheres in eight directions a few times before retrieving his scythe. This attack is based on two of Sigma's attacks from his first and second forms in Mega Man X4.
  • If the previous attack is successful, Sigma appears in the center of the room and fires several energy spheres on the player's direction.

Later, Sigma (X4 3rd form) appeared as the boss from the third Boss Raid in December 2020. His attacks are the same from Mega Man X4.^[7] Both forms later returned as Guild Boss battles, and the third form is also the boss from the event Host of Annihilation Droitclair.

Flame Demon Sigma, a modified version of Sigma's first form with a broom and a witch hat, appeared as the boss from the 2022 Halloween event The Demon of the Flames.

Other media[]

Rockman X4 manga[]

In the manga version of events, Sigma is first seen in an undisclosed, dark location with foggy skies, where he is seated with a dark cloak. He states that things are about to get interesting with the Repliforce and the Maverick Hunters and starts laughing maniacally as he begins his next plot. He hires Double, a shapeshifting Reploid to infiltrate the Maverick Hunters and join the 17th Unit where X is the commander.

In order to turn the Repliforce against the Hunters, Sigma cooks up a plot to have them framed for a big Maverick attack on a city. He has Double secretly set the Mechaniloid Eregion loose on a giant city, which causes millions of deaths. After Eregion is defeated, Double then plants Repliforce equipment at the scene next to the Mechaniloid's corpse to make it seem as if it was the Repliforce who orchestrated the mechanical monstrosity's attack. It works, and the Maverick Hunters accuse Repliforce of the incident and order that the organization be temporarily disarmed and disbanded. The Repliforce scoffs at disarming as an insult to their pride, and wage a coup against the human government for independence. However, Sigma is only seen once for the rest of the manga when Double reveals that it was Sigma who set the entire war up.

Gallery[]

Videos[]

Trivia[]

• This is the only version of Sigma where he is fought in all three of the final boss battles. While Sigma was fought in Mega Man X1 and Mega Man X8 with three boss fights, the former only had Sigma being fought in the second and third fights (the first fight was relegated to Velguarder) and the latter only had Sigma being fought during the first boss fight (the second and third were instead against Lumine).
  • Additionally, Sigma has more forms in this appearance than any other; his reaper form, Gunner form, Earth form, and trio of floating heads add up to four distinct bodies.
• In the PC version of the game, Sigma's first and second boss themes are swapped around.
• Interestingly, this is the only game where all of Sigma's audio pre-battle quotes are threats ("Tremble with terror! YOU ARE FINISHED!", "Prepare to become space dust!", "Are you ready for your final journey?!" or "Are you ready for round two!?", the last of which is uttered during the transition between the first round and the second round).
  • If the player is playing as Zero and gets to the third phase, Sigma will declare "Iris is waiting for you!", referring to Iris's demise earlier.
• Sigma's reaper form is the only time in any X series game where the player cannot progress without using a special weapon; it can only be damaged by X's Rising Fire or Zero's Ryuenjin.
• Sigma ultimately inciting the Repliforce rebellion under the rationale that humanity (and by extension, the Maverick Hunters) would ultimately destroy them or anything that isn't wholly subservient foreshadows Dr. Weil's conception, as the latter gives a similar description of humanity.^[8][9]

References[]

Mega Man X4
List of Mavericks
Web Spider • Split Mushroom • Cyber Peacock • Storm Owl • Magma Dragoon • Frost Walrus • Jet Stingray • Slash Beast
Other Bosses
Eregion • Colonel • Double • Iris • General • Sigma
X's Special Weapons
Lightning Web • Soul Body • Aiming Laser • Double Cyclone • Rising Fire • Frost Tower • Ground Hunter • Twin Slasher
Zero's Special Techniques
Raijingeki • Kūenbu • Kūenzan • Rakuhouha • Tenkūha ��� Ryūenjin • Hyouretsuzan • Hienkyaku • Shippūga
Armors
- X - Fourth Armor • Ultimate Armor - Zero - Black Zero
Stages
Sky Lagoon • Jungle • Bio Laboratory • Cyber Space • Air Force • Volcano • Snow Base • Marine Base • Military Train • Memorial Hall • Space Port • Final Weapon
Miscellaneous
Damage Data Chart (X) • Damage Data Chart (Zero) Mega Man X4 Script (X's story) • Mega Man X4 Script (Zero's story)

Mega Man X DiVE

Characters Main character The Player Supporting cast RiCO • ViA • iCO • Droitclair • Angepitoyeir • Eratoeir Other characters Eddie • Rush • Beat • Treble • Cyber-elves • Model X • Model Z • Lan Hikari • Eugene Chaud • Mayl Sakurai Hunter Programs X • Zero • Alia • Black Zero • Massimo • Axl • Ferham • Ultimate Armor X • Vile • Cinnamon Marino • Pallette • Layer • Mega Man • Proto Man • Super Mega Man • Roll • Iris • Zero (Z) • Leviathan Awakened Zero • Sigma • Ciel • Aile • Pandora • MegaMan Volnutt • Tron Bonne • Copy X • MegaMan.EXE • ProtoMan.EXE Bass.EXE • Omega • Magma Dragoon • Bass GS • Harpuia • RiCO • MegaMan Volnutt Alt. • Servbot • Roll Caskett Colonel • Iris -another- • Bass • Vile MK-II • Zero Nightmare • Rathalos Armor X • Dark MegaMan.EXE • Super Bass • Χ -kai- • DiVE Armor X Star Force Mega Man • Harp Note • Rogue • RYU • CHUN-LI • AKUMA • iCO • Dynamo • Bass XX • Roll.EXE • Fourth Armor X • Droitclair • Angepitoyeir • Gate • ViA • Gaea Armor X • Eratoeir • Nana • Bass Cross MegaMan • Dr. Light the Martial Artist Gameplay Deep Log • Cards • Deep Element • Irregular Data • Items • Script • Schedule • Stages • Weapons