In the Heroes Unite: Darkness Within story arc, L.E.G.E.N.D. was temporarily turned against his teammates by an override code issued by a Darkness-influenced Hellfire. Following this adventure L.E.G.E.N.D's programming was adjusted to make sure such a thing could not happen again.
When Heroes Unite were preparing to battle Energize, Amped uploaded a sub-routine into L.E.G.E.N.D. that overrode his restriction against lethal action. It is unclear whether this override applied only to Energize or was more broadly applicable.
L.E.G.E.N.D. is superhumanly strong and tough and has the ability to fly and fire energy blasts from his hands.