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