Saber Alter, also known as Dark Saber, is a villainess from the Fate series. She is the dark, evil version of the proud, idealistic servant Saber. She is voiced by the same seiyuu that voices Saber herself, Kawasumi Ayako.
Saber Alter makes several appearances in both the Fate series and Carnival Phantasm; in the Heaven's Feel route, Saber becomes corrupted by the darkness by Angra Mainyu and becomes Dark Sakura's servant, Saber Alter. Saber Alter abandons the ideals that the original Saber had, which easily disgusts Gilgamesh as he prefers the more idealistic Saber when she was resisting him. She also appears in Fate/kaleid liner PRISMA☆ILLYA, but a black face mask covers her eyes as a class card.
In Carnival Phantasm, she has several cameos in Episode 7 as both a figure and a figma, and in Episode 8, Saber becomes so angry and frustrated with Gilgamesh that she transforms into Saber Alter, whose darkness instantly attracts the men eating at Ahnenerbe, including Gilgamesh. She later reverts back to her old self as standard Saber when she comes back home to Shirou from work.
Saber Alter can be considered as a dead opposite to her older sister Arturia. Dark, violent and sometimes selfish, Alter can sometimes times be hard to deal with. Despite this, however, Alter can show some kindness and does care deeply for those close to her (her sisters especially). Like her older sister, Alter is bad in many social situations and often times gets embarrassed more easily then she would. Unlike her sister, however, Alter is prone to acts of violence and fits when embarrassed and is easily angered.
Saber Alter is a negative palette swap of Saber. Her skin and hair are even more pale, and her dress is black while her armor is darkened and becomes dark purple, with several blood-red linings painted on it. She carries a black sword with blood-red linings and has yellow eyes.
For casual clothes, she wears black gothic lolita fashion, and in Carnival Phantasm, while working as a waitress, she wears a black version of Saber's waitress outfit.
Saber was corrupted by the power of Angra Maiyu and became a servant of Matou Sakura. With an infinite amount of mana at her disposal her power increased accordingly at the cost of her agility and magical defenses. She can make up for her lack of speed with her prana burst which will still let her move at mach speeds. She is defeated in the Heaven's Feel scenario by a combined effort of Rider's Bellorophon and Shiro's Rho Aius used via Archer's arm which was transplanted onto him after he lost his own. Shiro dealt the final blow using Rin's Azoth Dagger and plunging it into her chest. In a bad end of the Heaven's Feel scenario Shiro fights Saber Alter one on one going past the limits of Archer's arm and is able to defeat her by using Archer's secret technique ending the battle in a draw. Saber lays on the ground defeated but regenerating but in exchange Shiro's mind was completely shattered. Saber Alter's raw physical power is equal to that of Berserker's and the firepower of her Excalibur is only surpassed by Gilgamesh's Ea.
Saber Alter is a medium speed attacker with heavy attack power and fire power. She has the fastest dash in the game(probably from using Prana Burst.) but also the worst dash after Dark Sakura's. Her 214A counter is perhaps the best in the game as it is not only reliable but can be linked into air combos. All of Saber Alter's air combos are capable of ending with her 236236B Excalibur making her have the deadliest air combos after Rider.
Saber Alter has a lot going for her if she can get close enough but she has a bit of a problem getting in there to begin with. She doesn't have Saber's super armor to break through and the first portion of her dash leaves her wide open and can't be canceled. If the enemy's a close range fighter you're all set since you can just play a defensive game but projectile users will give you hell. Against projectile users you will wants to time side steps with D and 2D to get closer. Risking 66 will likely get you a nasty projectile in the face. When you get close in you will want to use your 214A to open up since projectile users tend to use a counter as soon as you get up close and then send you back to where you started. Activating Prana Burst will probably strike some fear into smarter projectile users though as you can dodge and then blow them away with a long range Excalibur. Nothing is more satisfying than the look on a Gilgamesh player's face when you win the match by side stepping after he snaps his finger and then screaming "EXCALIBUR!" to blow away 75% of his health.