You have to jump and leap when you are spamming. Basically leave the FT with one of two choices, either aim and absorb the blast or move around and miss the shot. Because plasma is projectile based it works efficiently, you shoot, you leap, and while you are in mid air (where you mostly get shot) FT needs to dodge the plasma bolt.
Obviously against god snipers you’ll have trouble, specially if there’s more than one in the team.
Combining plasma with melee in close range also get’s them confused. I’ve been able to take down decent PC Death Squads with that. Playing very aggressive.