Phase one abilities:

Garuda will appear and cast a cone AoE on a almost half of the arena. This ability will deal approximately 1.7k to 2k to anyone in range.
At the same time, Ultima will use Vulcan Burst right when Minstrel Shriek is a about to go off. This deals around 450 to 600 damage and causes a knockback (Same as the ifrit fight.)
Using these two abilities in sucession, it is possible to be knocked into Garuda's AoE. Be wary of your position.

Ultima will also use Eye of the Storm, al la Garuda, and you must move to the center area of the arena. Do not collapse into he center though. After the wind dies down, Titan will fall from the sky and do Geocrush. You take damage from Geocrush based on how close you are to the epicenter, and at max range, you can take as little as 425 damage from this.