Mandalla was born on Takron-Galtos, the prison planet, because her mother was an inmate. At the age of 14 she left the planet and joined the legion Academy. I think she first apear in a comic in 1987, possibly a Legion Annual.
She can project a thought sphere to engulf her target, causing hallucinatory, distorting effects by interfering with one's bio-electrical system. Mandalla received intense training on how to use her powers.
The BG is from the talented Andead on deviant art.
Since I've done most of my fav Legionnaires, I think from this point it's Legion Academy members and obscure tryout rejects.
Long Live the Legion!