[Raeiphon]

Simple.

Make a -System npc and have actionprojectile trigger an event in -System (e.g serverside) and have that do the rest.

E.G -
//System NPC
if (actionprojectile) {
// use your params here, so:
//I dont know the syntax for hurt :O
hurt playerx,playery,#p(0)*2;
}