The Igdra Underground Church is seventh dungeon in the game.
Navigation through the church consists of pressing several switches scattered through the first three floors to unlock a set of doors at the bottommost area.
The church itself can by a daunting experience because of its plethora of traps,such as dark zones and non teleporting zones. There are also several warps that teleport the party to far way locations without warning, making this the most difficult dungeon up to this point, so bringing many magical maps is a must.
For this event, you need a Lv10 Bishop in your party, the head to Iguadola Church and listen to a man at the cobfessional. Go to the Igdra Underground Church, at B2F (x14,y2) and defeat the Sacrifice.
The party can find a Priest at the first floor, if you speak to him, the Degus Gila Ice Cave will become accessible.
This dungeon is considered one of the hardest dungeons in the game, particularly the first floor, which is full of teleporting areas, making navigation confusing and difficult. That plus the fact that the player will recieve no notice that they were teleported at all.