I've gone through this forum and there's no really comprehensive feats thread for Legion, which is a shame. He's one of my favorite characters. So I thought I'd make one, as I own practically every comic he's ever appeared in. The majority of his feats are here, but if I've missed something please feel free to upload it yourself if you have it or inform me and I'll upload it.
Name: David Charles Haller
Parents: Charles Xavier and Gabrielle Haller
Classification: Omega-Level Mutant
Ability: Possesses thousands of mutant abilities, ranging from telekinesis to cosmic-level reality warping. However, each power is controlled by a different personality, which may be either benevolent or malevolent. As such, Legion has thousands of different personalities at the moment.
The powers he's displayed and the feats associated with them are below:
Xavier uses his astral form to try and probe Legion's mind, but he just laughs and throws Xavier back into his body and out of the room.
Unleashes a storm of psychic energy that destroys Muir Island. Xavier and Co. need to wear special psi-suits to protect themselves from the energy.\
Shuts down Forge's mind.
Forces Magneto to relive the worst moments of his life.
After travelling back in time to kill Magneto, he is attacked by the X-Men. Iceman freezes every molecule of Legion's body, but he breaks out after releasing a psi-wave that knocks out Storm, Bishop, Psylocke and Iceman.
Attempts to kill Magneto with his psi-blade, but Xavier jumps in the middle and is killed instead. This causes the Age of Apocalypse.
Facing the rogue personality Chain, Xavier struggles to read his mind. However, Legion manipulates Chain's copies with ease.
Pulls Mystique into his mind, and then spits her out unconscious.
Engages in an all-out, city-busting battle with Magneto. Legion uses his TK to beat up Magneto and render him incapable of fighting back.
While being thousands of miles away, he uses his TK to throw a sleeping Magneto out of his bedroom.
While under the control of the Shadow King, he blocks a plasma cannon's attack and then freezes all the members of the X-Men and X-Force in place.
Magneto's attacks don't put the slightest dent in Legion's TK shield.
Roasts Storm in mid-air.
Creates a nuclear-level blast that levels Muir Island.
Blows up a room in Muir Island.