Mission 7 - Pieces of a Mirror | Piles of Sacrifice and Dungeon Keys - First pass Castlevania: LoS 2 Guide
Last update: 11 May 2016
#7 Pile of Sacrifice and #4 Keyhole for a Dungeon Key
After regaining control, don't go towards the castle (ahead), but turn around and go to the device. Destroy the ice blocking the device with a Chaos Bomb, and then pull the lever. Pass through the bars blocking the way and go through a tunnel on the right side.
Stand on the edge and jump on a small stone ledge - behind the bars you will find a Pile of Sacrifice, which will award you with another Kleidos' Nail. Ignore the further part of the tunnel (as you lack a skill necessary to get there), jump down from the ledge, and then get inside the tunnel on your right side.
After entering the tunnel, go to the right, where you will find two Pain Boxes (with a Void and Chaos Gem inside). After collecting both gems, go to the right part of the tunnel, where you will find a keyhole for a Dungeon Key (you were here during the Buiquimek Corporation mission, but you didn't have any keys on you at that moment.
#5 Keyhole for a Dungeon Key
Get outside and hop on a wooden bar to start climbing - after getting to the crossing, move all the way up to reach a place with a keyhole for a Dungeon Key (again, you will receive 2,000 points of experience for unlocking it).