Titan Hard Mode Strategy

HM Titan is an enormous change from Ifrit and Garuda.
Not only is the fight LONG, there is an enormous amount of damage taken by the entire party.
-You will have to excuse my horrible MS Paint skills for this.

First of all: This fight almost renders a gear check as a necessity.
Under 3.4k hp, and it will be incredibly difficult for a healer to keep you up in Phase 3.
If you are a DPS without at least an ilvl 60 weapon, it will be difficult to burn fast enough in Phase 2.

So, once you are satisfied with your gear and ready to begin, read on.

General guidelines for this fight:

Stay spread out, and keep moving.
If the group is too close together, weight of the land will stack together and make it incredibly difficult to reach safety.
Titan generally uses an ability every 4-5 seconds, so if you have slight latency issues, count to 4 after the end of one cast, and start moving in advance. This will save your life.

In order to get the most room for movement, I recommend fighting Titan in this position:
http://i.imgur.com/HGVQEvt.jpg
This allows for melee to quickly break, and for more room for ranged classes to maneuver.

Now that you are in position, lets get into the thick of things.

Phase 1.1: The pull
Simple stuff, the tank simply needs to pull Titan into position, and start building aggro. Everyone else gets into position.
Titan will use 2 abilities at this point, which you should all be familiar with from the story fight:
Landslide: Titan will raise his arms, and send a massive shockwave in a line, knocking anyone hit off the edge. Simply sidestep this to avoid it.
Tumult: Titan will stomp the ground, dealing between 600-800 damage per stomp. For phase 1, he only stomps 2-3 times. Healers will want to move towards the centre of the arena, and cast Succor/Medica in order to get everyone back to full.
At the end of the phase (~85% hp), Titan will leap up, and slam down in the centre, dealing damage based on how close you are. If you are in the red on the outside, you will most likely fall off, so careful! Sacred Soil and Succor work for mitigation here, as being right on the outside of the ring will still deal ~1,800 damage to everyone. Precast Succor/Medica II and break off once he lands, and you are into Phase 1.2.

Phase 1.2: Heavy
Now that Titan has broken the walls, you can fall off the edge if you are not careful. A single landslide means someone is dead and unable to be resurrected. If that is the case, everyone should just jump off and wipe now, because you will not be able to kill him this attempt.
For Phase 1.2, Titan will also cast another skill:
Weight of the Land: Brown circles appear underneath people (not the main threat target), and after 2 seconds, they will explode, dealing ~2,000 damage each after mitigation. This is why everyone needs to spread out, as 2 hits from this will be an instant kill for anything except a tank. Watch his cast bars, and if he begins casting this skill, simply move forward. This will get you out of any AoE. For phase 1, Titan only places 3 AoEs.
Again, he will leap up at the end of this phase and do another stomp, knocking off more of the arena (~70% HP), so heal up and move on to Phase 1.3.

Phase 1.3: She's Gonna Blow!
It's getting serious. Titan will start mixing in two more skills here, as well as possibly another hit of tumult. Again, these spells are cast ~4 seconds apart from each other (from the end of the cast bar, NOT the resultant damage). This means that skills can start while bombs are littering the field.
Bomb Boulders: Titan scatters the arena with bombs, which detonate for large amounts of damage (~3k?) after a certain amount of time. They are in very specific arrangements, only two of which are used in Phase 1.
Clock Arrangement
http://i.imgur.com/ZwiFXTt.jpg
Bombs will appear in the order noted (This can begin at ANY orientation though).
You will want to run to either the #8 or #9 bomb/position, and then move towards the #1 as it explodes.
Box Arrangement
http://i.imgur.com/xHq9P31.jpg
Bombs appear as noted (3 sets). The only safe locations are between the #3 positions, along the edge of the arena. If you are there, you do not even need to move.
Titan will also use one more ability, which you will remember briefly from the story fight:
Granite Gaol: One player (not the main threat target) will be encased in rock, and be unable to take any action, or be targeted. In general, DPS is to break this open ASAP, however there are two exceptions to that, which I will note as they come. One advantage to this gaol, is you cannot be damaged while it is up. Once it is broken, whoever was in it needs an esuna/leech, because the determination debuff is quite strong.
Finally, once Titan is down to about 55%, he will leap once more. Heal it up and move on to Phase 2.

Phase 2: Heart Breaker.
You would remember this one from story Titan, his heart is exposed and must be burnt down QUICKLY. If you do not succeed, he will leap up, and cause a nuclear explosion, instantly killing the entire group. A melee DPS needs to use limit break here. If you are almost at 2 bars, wait until 25% on the heart in case you get the second filled. If not, you may as well burn it straight away.
Through this phase, he will NOT cast any bombs, but he will use every other skill.
He will cast gaol twice through this phase. You need to break the first one open ASAP, however you will then need to ignore the second one. If you don't it is unlikely you will have the DPS to kill the heart.
Once the heart has been destroyed, kill the last gaol immediately. You will want to get every damage mitigation spell up on the group possible (Sacred Soil, Succor, Medica II regen), and then precast heals. This nuclear explosion that he uses will still deal 2.5-3k damage AFTER mitigation. You will need to heal this up ASAP as you move to Phase 3.

Phase 3: Flippin Tables.
That was the easy part. You will need immense amounts of focus here, or you will be in trouble.
Titan will use every single ability that he has used so far, on steroids, in addition to what we lovingly like to call, the table flip.
Weight of the land will now spawn 5 AoEs. You also have a much smaller area to move around in.
Tumult will be used for upto 8 hits in a row (double chained 4x), totalling 4,200-6,400 damage to the entire group. Healers need to be absolutely on the ball here. Generally, he will use weight of the land at the end of tumult, so be ready to run.
The biggest thing to watch out for here is the TABLE FLIP. This attack has no cast bar, but has a decently visible wind up. It will deal ~4k damage to a PLD in full ilvl 70 gear. If the tank is not topped up, he will die. Titan also likes to follow this up quickly with another 2k swipe. Healers need to keep PLD topped up here as much as possible, while also having mitigation skills up. Scholars, rotate Sacred Soil, Eye for an Eye, and Virus here, as well as maintaining Adloquium. White Mages, it would be helpful here to put Stoneskin up if you can. You must precast heals here in order to keep the tank topped off after table flip.
There is also a new arrangement for bombs!
Marching Arrangement:
http://i.imgur.com/FgDmL2F.jpg
Bombs will drop in three lines, in the order noted. Note, the orientation of this could be any, even with the tank being in the middle of the #3 line. Everyone needs to run to the #3 line, to the MIDDLE bomb in that line. Titan will use a landslide while you are here, and you need to break to the side bombs to avoid it. Once the #1 line (centre line) explodes, you need to rush there, then return to initial positions.
BE CAREFUL HEALERS: Titan will use TABLEFLIP as the bombs finish detonating. You will need to make sure the tank is topped off.

If you have all of this under control in Phase 3, then you are doing well These abilities are just repeated for the last 50% hp. The transition from Phase 2 nuclear explosion to Phase 3 is the real kicker, because everyone is low on health with an incoming table flip.

Congratulations! You may have now killed Titan, allowing you to finish your relic and enter the Binding Coil of Bahamut!