So Here is what you do:

1. before a fight, Precast Ruin III/Tri-disaster (for AOE) to get into combat (If you are lvl 70 or above you can skip to next step though its not necessary)
2. Hit Dreadwyrm Trance/Firebird Trance
3. Spam Astral Impulse, (Purple Bahamut button for Single target, Green Bahamut button for AOE) and use your oGCDs (Energy Drain, Festers, Ahkmorn and Deathflare) /// Same transfers to Phoenix, Dark red for Single target, Orange for AOE
4. Once you end trance, use a egi summon (Topaz/Titan, Emerald/Garuda, Ruby/Ifirt)
5. Use your recolored Ruin III/Tri-disatser spells, called Gemshine/Precious Brilliance Till you run out of charges for the egi (4 charges for Titan and Garuda, 2 for Ifrit)
5a. The charges and current egi can be seen on your Job gauge, hence the crystals
6. Repeat step 5 untill you used each egi once. Use your Ruin IV from energy drain when you best see fit but not during a egi window, Cast Ruin III untill Trance is off CD
7. Start at step 2

Basicly you summon Demi, then 3 egis, them Demi again. filling any empty space with Ruin III & IV, Use energy drain off CD, and if possible save festers for your Searing light windows which should line up with bahamut pendin on SPS.

Note, Carby is just a cheerleader now who gives a shield, for now.