if you want a unit do splash damage set up aoe damage and targets + missle (splash) in the units object editor. to make a unit do fire multiple projectiles use the barrage ability.
if this is not what you wanna know explain it a little bit.
yes it's from the barage ability and i made it from warcraft site for help on world editor. i followed there instructions and my unit/tower can't do multiattack!! i dono know what else to do..
a bit more:
a made a tower from priest unit
deleted all his abilities
and gave him the barage ability
first under object editor, under unit, select your unit, under combat - attack 1 - weapon type, select missile.
second under object editor, under ability, select your ability (Barrage), stats area of effect, make it equal to your attack range, While make the cooldown 0 and the duration 0.1. Finally stats - target allowed tick enemy, air (if you want to attack air), ground (to attack ground unit)
it should work, if still can't please post your ability data here
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.