Here is the full list of all 16 Demons with Shotguns achievements.
Flawless Victory!
You kept killing yourself.
You don't seem to understand how ammo pickups work.
You collected 500 souls!
You earned a Antichrist kill streak.
You earned 3 Monster Kills.
You earned 5 Double Kills.
You completed Ghosts n' Nomeds.
You jumped 100 times in one match.
You used 10 tarot cards in one match.
You're an a' hole with how much you taunt.
Fighting for scriptures.