function CasterAreaDamage takes unit Caster, real X, real Y, real R, real Damag returns nothing
    local group gr = CreateGroup()
    local real u
    call GroupEnumUnitsInRange (gr, X, Y, R, null )
    loop
        set u = FirstOfGroup(gr)
        exitwhen u == null
        if u != Caster then
            call UnitDamageTargetBJ( Caster, u, Damag, ATTACK_TYPE_MELEE, DAMAGE_TYPE_LIGHTNING )
        endif
        call GroupRemoveUnit (gr, u)
    endloop
    call DestroyGroup(gr)
    set gr = null
endfunction