Items Needed:
Silent Oil/Prism Powder - minimum 1 stack of each(required for melees, suggested for mages) (for travel to/from most ZM)
Poison Potions -4 (required for mages only) (ZM-4 and ZM-6)
Ice Clusters - several for the group to get through flame spouts (ZM-5)
Echo Drops - 2 stacks (all casters) (ZM-6 and ZM-8)
Delkfutt Key (obtained by killing Porphyrion in Upper Delkfutt's Tower) - not required, but saves a LOT of time (ZM-8)
HP/MP drinks - A sufficient quantity for a BCNM battle (ZM-8)

ZM-4
BCNM Fight against 3 Tonberries, a THF, BLM and SMN. Kill order is as follows:
1. Tonberry Grav'iton (THF)
2. Tonberry Molyb'iton (BLM)
3. Tonberry Tungs'iton (SMN) + elemental pet

The BLM and SMN are slept while the party kills the THF. Tank, BLM (or BRD), WHM + DD's required for this BCNM.

After winning this battle, you leave through a different gate, so we will need to carefully consider party setups in the hopes of avoiding running back to the Sacrificial Chamber.

ZM-5
Collect 7 elemental fragments from all over Vana'diel (you will have obtained a dark fragment upon completion of ZM-4). The fragments are obtained from headstones, and touching 4 of the headstones pops a NM (or NM's).
Behemoth's Dominion (fight 2 weapons) - Depending on alliance size, the weapons may be fought simultaneously. The other option is to have the alliance fight one while the 2nd is solo'd by a blink tank (or duo'd with mage support). Once the first is killed, the alliance finishes off the 2nd.
Yuhtunga Jungle (fight 2 monkeys) - The trip to this headstone requires travelling through Ifrits Cauldron. There are many bombs that aggro magic and sight, so it is suggested that mages bring oils/powders to avoid getting bomb aggro from casting sneak/invis. Strategy the same as above.
(note: trading a garnet to the headstone yields an Opo-opo Necklace)
Cape Terrigan (fight 1 shadow) - Blink tank preferred because Dimensional Death damage is absorbed by shadows. Goblin in vicinity needs to be killed before popping this NM.
Sanctuary of Zi'Tah (fight 1 undead flesh) - Blink tank preferred because this NM hits pretty hard.
Fragments need to be collected in the following zones (no fights required): Cloister of Ice (through Fei'Yin), La Theine Plateau (via Ordelles), West Altepa (via Quicksand Caves)

ZM-6
Fight 3 anticans in Quicksand Caves. Similar strategy as ZM-4. Echo Drops required as anticans have AoE Silence. Poison pots recommended for mages in case the BLM Sleepga's. Mages need to keep Stoneskin up to protect against Eagle Eye Shot. Kill order is as follows:
1. Centurio V-III - PLD
2. Princeps V-XI - RNG
3. Triarius V-VIII - BLM

ZM-7
Cutscene in Chamber of Oracles.

ZM-8
BCNM fight in Stellar Fulcrum (through Delkfutts Tower). HP/MP drinks, Echo Drops needed. Enemy uses Dispelga, AoE Gravity, and WS "Light Blade" that does a lot of damage. Enemy also occasionally resets all hate, often after doing Dispelga or AoE Gravity.

ZM-9 through ZM-11
Walk around and talk to people. Recommend setting home point in Norg temporarily.

ZM-12
Fight a Magic Pot NM and then click on a ???

ZM-13
Another cutscene and Sky access!