This achievement is a doozy. You must complete 13 objectives in one game. Once you complete Midnight mode, the obsidians are available to obtain again. You do not need to obtain 13 unique obsidians for this achievement, just 13 total.
1) GATES TO THE VOID: Shoot the three drop targets in the middle of the playfield to reveal the cellar entrance. Drop down to activate a random game mode. In this mode, 4 blue glowing gates will appear on the table. You must first sink the ball in the "whisper" target to make your ball glow blue. Then shoot the 4 gates before time expires.
2) BONES: Shoot the three drop targets in the middle of the playfield to reveal the cellar entrance. Drop down to activate a random game mode. The 3 bumpers on the left side of the table and the spinners are active to score points. Shoot the ball into the far right spinner which then travels to the bumpers. Hit the targets fast enough to escape the skeletons and win the game mode.
3) ARACHNID ATTACK: Shoot the three drop targets in the middle of the playfield to reveal the cellar entrance. Drop down to activate a random game mode. 5 spiders hang from the ceiling. Keep hitting the spiders without draining the ball until the Escape is lit. Shoot the escape to win.
4) BEHIND THE WALLS: Shoot the three drop targets in the middle of the playfield to reveal the cellar entrance. Drop down to activate a random game mode. This time there are multiple gears and levers. Use the flipper buttons to change direction of the gears and levers to make your way to the exit.
5) CRAZY GHOSTS: In this mode, 6 ghosts appear at the entrances to the ramps and lanes. You must hit all 6 ghosts quickly to clear the mode. If you take too long, the ghosts begin to respawn.
6: CREEPY CELLAR: Shoot the three drop targets in the middle of the playfield to reveal the cellar entrance. Drop down to activate a random game mode. Shoot the flashing lanes until the escape route lights up. Shoot the escape to complete the mode. This mode is very similar to Arachnid Attack.
7: FREAKY FOREST: Shoot the far right or far left lanes 6 times to activate this mode. The tree will lean over and block the Citadel ramp. Shoot the ramp, thus hitting the tree, 3 times before time expires to complete this mode.
8: TOWER CRAWLER COMBO: Shoot the three drop targets in the middle of the playfield to reveal the cellar entrance. Instead of dropping into the cellar, shoot the stairway to 8 times to spell "Stairway". The next shot into the Whisper hole will start the mode. You must complete 3 shots up the stairway before time runs out. This also unlocks an achievement.
9: ELUSION MASTERY COMBO: Shoot the ball between the left bumper targets around to the upper right flipper. Make the shot with that upper flipper onto the Ghost ramp for an Elusion Mastery shot. Do this 5 times to obtain the obsidian.
10: MULTIBALL: Shoot the center spinner and immediately use the upper right flipper to shoot the ball into the open Gargoyle gate to lock the ball. On the third lock, multiball begins. During the multiball, all 7 main shots are available to collect Jackpot. Shoot all 7 then make the Super Jackpot shot on the upper left hand playing area to score the obsidian.
11: SORCERER MULTIBALL: Every 3rd shot to the Left Tower Ramp takes the ball to the sorcerer's pedestal, which locks the ball. The third lock starts multiball. There are three flashing targets, far left lane, far right lane, and the staircase. Once you hit all three, then shoot all 3 balls up the Left Tower ramp to complete this mode. You MUST maintain all 3 balls to complete successfully. This also unlocks an achievement.
12: Whispers random drop. Thanks to SOLO NO1.
13: Hit whisper in the first a stage of midnight madness. Thanks to SOLO NO1