How the hell do you beat the dreglord 😭😭😭

I've got to this mf several times and phase 4 is always where my team dies. I kinda understand phase 1 with the enemies buffing him and I've learned some of his attacks but phase 3 and 4 he starts moving like he's on crack and hits like a truck

Furthest I've gotten is maybe halfway through phase 4 maybe before that idk