Vana'diel Bestiary: Fubruhn  

Expansion to 40

* 4x Imperial Mythril Pieces to Fubruhn

Expansion to 50

* A Conquest Tally must pass after the first expansion.
* 2x Imperial Gold Pieces to Fubruhn

Expansion to 60

* A Conquest Tally must pass after the second expansion.
* 3x Imperial Gold Pieces to Fubruhn

Expansion to 70

* A Conquest Tally must pass after the Third expansion.
* 5x Imperial Gold Pieces to Fubruhn

You need to talk to Salaheem first and do your first Runic Portal before he'll talk to you, though fortunately that's not too hard. From Nashmau, leave through the North gate into Caedarva mire. You will need Sneak/Invis even at level 75. Once outside, follow the left wall through the first cave, and from there, head straight to the opposite wall. Turn left, but follow the right wall. Eventually you will go through another cave, at which time you should start following the left wall. Only a little bit further, and you'll come to a giant set of doors. Pass through and talk to the NPC just inside. Voila. Use the runic portal, then go to see Salaheem again, and you're done.
Fubruhn will give you a mog locker to use for a fee of 1 Imperial Bronze Piece. The mog locker holds 30 items from the start. The duration of the lease changes depending on where you choose to access it. If you leave it in Whitegate only, it will cost you 1 Imperial Bronze Piece for 7 days. If you choose to make it available in Sand'Oria, Bastok, Windurst, and Jeuno as well, then it will only last 5 days.
You may expand your mog locker by 10 spaces once per Conquest week (every Sunday) three times, for a grand total of 60 spaces.