The armor bonus for 4 pieces of the Deep Stone Crypt set (which launches a swarm of missiles upon super cast or shield break by a combatant) has a bug. Its missiles, as far as I can tell, do not actually count as missiles. They have the blue keyword text, but for example, do not work with the exotic Hazardous Propulsion, and are unable to receive its damage increase. Ironically the missile swarm appears to be an exact 1-1 copy of the one found on the sticker shock artifact perk, which DOES work with hazardous propulsion. So yeah, deep stone armor missiles aren’t actually missiles despite using the blue indicator text