The only way I managed to beat Titan HM was with a premade that included:
x3 healers(x2 WHM / x1 SCH)
x4 DPS (No BRDs or SMNs *they die the most during HM Titan)
x1 Tank (PLD aka Me)

Took us two tries to kill him only because the second time we used the first phase for LB3 stacking. Now I have to go against the EX Primals and doubt I'll try it again.....going to grind CT until new content.