function damageFilter takes nothing returns boolean
    if(IsUnitType(GetFilterUnit(),UNIT_TYPE_STRUCTURE))then
        return false
    endif
    if(IsUnitDeadBJ(GetFilterUnit()))then
        return false
    endif
    if(IsUnitAlly(GetFilterUnit(),GetOwningPlayer(GetTriggerUnit())))then
        return false
    endif
    return true
endfunction

function damageFunc takes nothing returns nothing
    call UnitDamageTargetBJ( GetTriggerUnit(), GetEnumUnit(), 200., ATTACK_TYPE_HERO, DAMAGE_TYPE_NORMAL )
endfunction

/*

...

*/

// trigger actions
local group grp = GetUnitsInRangeOfLocMatching( 300., unitDamager, Condition( function damageFilter ) )
ForGroupBJ( grp, function damageFunc )