You can cast an area spell with a casting time of 1 standard action or less through a ranged weapon, allowing you to use the weapon’s range rather than the spell’s range. You must target a single creature with your attack, and the spell’s area is centered on that creature, or originates at the creature’s location for a cone or line effect (oriented in whichever direction you choose), even if the spell would normally be centered on or originate from a point. You can fire the weapon as part of the standard action to cast the spell. You must fire the weapon during the round that the casting is completed, or the spell is wasted. If the attack misses, the spell is wasted. Spells with an emanation effect that would be centered on you don’t benefit from this magic hack.

A weapon with the spellthrower fusion is able to have a single spell gem loaded into it at a time. It takes 1 minute to load a spell gem, and only gems containing a spell with a casting time of one standard action or less and a spell level no greater than one-quarter the weapon’s item level can be loaded into the weapon.

If you are proficient with and wielding the weapon, as a full action you can cast the spell contained within the spell gem rather than make a normal attack. This allows you to use the spell gem as if you were a spellcaster with the spell on your class’s spell list.

Unlike the normal rules for using a spell gem, it does not matter if the gem’s item level is higher than your caster level (even if your caster level is 0). However, if the spell gem’s item level is higher than your base attack bonus, once you’ve spent the full action to cast the spell, you must succeed at an attack roll with the weapon against an AC equal to the spell gem’s level + 1 or you fail to cast the spell. This roll represents your expertise with the weapon, and no actual attack or ammunition is used. If you fail to cast a spell from a spell gem, the spell is expended harmlessly and the spell gem is destroyed.