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