for me its 2 ways:

1 nuke him and he's dead but most of you will die.

2. strategy way, live but a pain in the buttocks for ranged box team.

mostly movement and knowing when to move when he sits on your face. i use strafe, team weaves in and out of wells and then follow tank during phantom blast and spread again for more wells.

during the beam, its so so important quickly judge which direction its going i fail alot here because im not paying attention enough and can wipe. i have done this flawless a few times only because its 50/50 on which direction the beam goes.

but the best advice i can give on the beam is to soon as it starts move the group immediately chances are you more likley to survive and avoid the beam. by this phase you would of killed him while he beaming the otherway