If you die on the platform you can be revived but if someone falls down from the platform he is out of the fight and has to wait he can only join again if the hole goup dies.
At the beginning you only make damage on Titan. If his heart spawns you have to switch to it an kill it as fast as you can. If you don't kill it in time he makes his special attack and everyone dies.
Thats why you should save the limik break for the heart.

You have to watch out if the stomps on the ground... run out of the are or you gonne fall from the platform.
When he puts someone in the stoneprison you have to make damage on it to get the player out.

Ok i hope this helps a little bit :P I am gonne fight him again tomorrow (hope so).

Sorry for my bad school english.