Dragon's Dogma 2: Martyr's Bolt
Youtube (Final Boss spoilers)
Does more damage the more self-damage you take to your health
Dragon's Dogma 2: Unmaking Arrow
Insta-kills any enemy in the game, but can only be fired once, and auto-saves after you fire it
Borderlands 2: The Interfacer
Consumes 2 ammo per shot. Fires slow-moving projectiles than spawns two additional projectiles in a horizontal row on either side of the original projectiles, which then flare out and reconnect with their parent projectiles. No movement speed penalty when aiming down sights. 60% Critical Hit bonus – Source
Borderlands 4: Roulette
Lord Luck – On Reload, gain random buffs. (x2 Fire Rate, +1 Pellet Count, x2 Crit Damage, x2 Damage, x2 Magazine Size, x2 Reload Speed, x2 Accuracy)