This is a phase 3, randomized, double-blind, placebo-controlled, multicenter study that evaluates using ravulizumab infusions as treatment for patients with generalized Myasthenia Gravis. Participants will receive either ravulizumab for the duration of the study or placebo during the 26-week randomized-controlled period of the stufy and then enter the open-label extension period where they will receive ravulizumab. The main outcome will look at the change from baseline in Myasthenia Gravis-Activities of Daily Living (MG-ADL) score at week 26 (end of randomized period).