Below are the good farm locations in 12sky2. If you need some assistance to making money, then read this portion.

At high lvls you can easily solo them, and at the end there are 3 bosses. Dont be scared, they do about the same damage as the normal mobs from the dungeon, and you can kill them as quikly. The items droped(often) from these bosses are eather sloted titan.(200k-400k), UCH, UCM, or 2 sloted armours. Sometimes they drop FCH, or cheap amulets/rings, but that happened to me so rare, that i think its irelevent.

Try going to the bosses as fast as you can. After you kill the bosses, leave at least 1 mob, inside the room, alive. This will cause the dungeon to not end, and this will cause the bosses to respawn, in about 6-8 minutes. So you will have 6 definit drops, + the drops from the mobs.

Ruina Station
One of the best places to drop lvl3 disks, which you can use for craftin' , or sell to crafters. Kill the bosses as fast as you can, and grind at the mech buffalo's+, even after you kill the boss(bear) in that place. Grind, and wen there's about 10-8 minutes left of RS, go for the last boss. You never know what the chest can drop