Once you have hit 6-8 pieces of Darklight gear (average item level of 65+), you are ready for the Crystal Tower. This is a 24-man dungeon which drops item level 80 pieces (Darklight is item level 70; Tomestone of Mythology gear is item level 90). It also provides 200 Tomestones of Philosophy and 50 Tomestones of Mythology for each completed run. However, you can only loot 1 piece of gear from Crystal Tower each week (resetting on Monday at 10 AM).
Note: Tanks should reach an average item level of 70 – full Darklight or better – before entering Crystal Tower. It can be done with a tank in lower-level gear, but for the typical pick-up group a tank under item level 70 would be a burden.
Once you reach this point, after the reset, you will want to run the Crystal Tower until you get your item level 80 piece, collecting Tomestones of each type along the way. This will give you 1 item level 80 piece each week and help boost your Tomestone counts in the process.
During this same step, you should unlock your relic weapon. While upgrading from a grand company weapon to your Relic will be a massive upgrade, I put this in a later step simply because you do not gain a real advantage from getting your relic early. However, you are limited to one Crystal Tower and 450 Tomestones of Mythology each week, so you will want to hit this quota first, then go for your relic weapon in your spare time.
You can pick up the relic weapon quest in Vesper Bay from Nedrick Ironheart. There are plenty of guides out there on this topic if you need help at any part during the questline. With this level of equipment, you should have no problem completing any aspects of the relic quest. It is not too difficult to find groups or a few players that will carry newbies through Titan. This process used to be quite formidable, but enough players know the fight and enough players outgear the encounter that it is fairly trivial these days.
Unlock your relic, pick up a piece or two of Crystal Tower gear, and use your excess Tomestones of Philosophy to finish your Darklight set. This process will only take two weeks at most if you play an hour or so a day.MORE:ff14 gil