Origin

The Three Mothers are three warrior queens of unknown lands from beyond the outer planes. They are vanguards of the Peregrine Child, a being of unknown origin that feeds on powerful beings of magic. The Three Mothers were tasked on scouring the lands for beings to feed to the child.

Creation

They first appears in Death of Doctor Strange #2 by Jed MacKay and Lee Garbett

Major Story Arcs

Death of Doctor Strange

The Three Mothers found their new prey to feed to the Peregrine Child: the dimensional warlords Umar, Tiboro, Dagoth, and Aggamon. Although, they are usually rivals, their combined strength wasn't enough against the Three Mothers. Instead, they conspired with a lowly sorcerer on Earth, Kaecillius. The warlords upgraded his magic so that he could kill Earthrealm's Sorcerer Supreme, Doctor Strange, thus weakening the barrier that was keeping them from invading. The Three Mothers would follow, but they hoped that the champions of Earthrealm, like the Avengers and the X-Men, would help protect them.

Luckily, Doctor Strange had a resurrection spell ready in case of his untimely death. He was able to strategize against the mothers and their child. He managed to convince four other realms' sorcerer supremes to combine their power and halt the mothers in their track. Meanwhile, Strange would send his astral form after the child. The child would consume him whole, and, while conscious in the child's gullet, Strange would absorb the magic to slay the child and scatter the mothers across multiple dimensions. Without the child they would be stranded.