Finally, another blessed card for Father Mateo. Unfortunately he’ll never use it because he doesn’t have access to firearms, so it seems the only reason they have the “blessed” tag on this is for flavor. Just upsets me that all blessed cards are either worthless to father Mateo or already in his class. Just my thoughts on the card though.
Upgrade. Supply. Blessed.
Fast. Play only during your turn.
Attach to a Firearm asset controlled by an investigator at your location. Place 2 ammo on that asset. Limit 1 per asset.
Attacks performed by attached asset deal +1 damage against Monster enemies.

As I'm currently using Marc Harrigan for the Forgotten Age, this card feels like it might be a highly viable replacement for the Extra Ammo card I currently have stacked under Stick to the Plan.
Fast (but only during your turn) is getting overlooked, and it's a big advantage. Especially if you have a shotgun with one less ammo than you need, but you still need all three actions to kill that Immortal Elder God from Beyond the Time. Plus you can reload something without getting attacks of opportunities, which makes it even more useful against suprise monster ambushes from the Encounter Deck.
On Marc this essentially allows you to break the 5 damage hard-cap on Shotgun against the only enemies that are going to need it. All of a sudden, your shotgun goes from being able to do 15 damage max a turn to 18. That's a reasonble jump, and doesn't factor in any Vicious blows, Beat Cops or Home Front nonesense.
At 3 cost and 3xp, I'll personally be holding off getting it until I upgrade at least one of my Emergency Caches to the 3xp version, and only one copy of it for Stick to the Plan, but I can definitely see it being part of a slowly building monstrous combo with Shotgun Marc that enables me to kill Elder Gods in a turn.
Hello.
I'll be adding this to my Zoey deck with two Well Maintained arkhamdb.com Combined with Stick to The Plan with one (or maybe two) Act of Desperation arkhamdb.com and Contraband I am hoping her BAR will keep bouncing....
Feels like this is a card for Zoe! Flamethrower is best suited for her, as she wants enemies to be engaged with her. And flamethrower with custom ammo can do up to 30 damage total in a monster heavy scenario. That's 2 more than extra ammo can give you. It's not cheap for guardians, who a always low on cash. Fast is really needed here. Zoe in a tough scenario can engage a lot of enemies, get resourses, and pay for custom ammo without AoO. With that tactic you'd need something like Narrow Escape, which she could take.