Legacy was born sometime after Grunt's heroics at the Collector base. He was raised in the Urdnot camp by his mother and was known as one of the strongest children to be born to Urdnot since Urdnot Wrex.
He was strong, strong to the point that he figured he could learn nothing from the Urdnot Clan and was destined to be it's teacher instead. He banished himself from the clan and travelled the war-torn world of Tuchanka, conquering beasts and documenting his exploits. He returned to Urdnot to complete his Rite of Passage and managed to topple a Thresher Maw alone. After this, he went on a campaign to build his stature among the denizens of Urdnot.
He bred with the women who he saw worthy of carrying his genes and toppled some of the greatest warriors in sparring matches and duels. Later on, when Urdnot Wrex's ship was unexpectedly destroyed, Legacy became the Urdnot Clan leader. He began a new campaign; a mission to assimilate every krogan clan into Urdnot. He eventually did so through warfare and negotiations and created the Tuchanka State Union.
He revamped the reconstruction effort that was the United Krogan Front and managed to uplift the krogan in only a few decades. Meanwhile, he had krogan scientists use his genes to create an army of pure-krogan; just like him and his father. Because they were both male and female, they gave Legacy the perfect chance to do what he truly wanted for the krogan; a new beginning. Legacy gave the order for the secret Krogan Purge soon after this army was created and many of the original krogan had been replaced by pure-krogan.
Legacy continued to build his new empire soon after the Purge.
Legacy has an incredible ability to manipulate others, even the strong-willed krogan that have found themselves serving under him. He has a near-photographic memory and despite his brutish appearance, is quite brilliant. Legacy is naturally an incredibly-skiiled fighter with an adept skill in all forms and weapons of combat. These skills are only amplified by his cybernetic implants. He has a cerebral implant called a Berserker Implant that allows him to actively switch in and out of the krogan berserk state which makes him very dangerous and unpredictable.
Legacy also has multiple augmentations to his bones, muscles, and organs which increase his durability and strength. Legacy's armor also gives him an edge over all that come against him in combat; his armor has been specially outfitted to support a Gravity Pack which gives him the ability to manipulate the mass effect field around himself and fly. His armor has both a Fortification mechanism, Tech Armor, kinetic barriers, and a new shield type called a Pulse Shield which blocks most solid projectile weapons and launches a pulse wave that can cause severe injury to those in the nearby vicinity.
He is also equipped with a Maximus Gauntlet, an advanced form of omni-tool developed by the Tuchanka State Union, which provides him with control over large amounts of drones and VI for a long remainder of time and it increases the strength of ordinary tech powers by nearly ten fold.