Header

    globals
        BuffType BT
        BuffType CD
        Cast C
    endglobals
    
    function overgrowth_dmg takes DummyUnit C returns nothing
        local Creep U = Event.getTarget()
        local Tower tower = C.getCaster()
        set Event.damage = 0
        
        if U.getBuffOfType(CD) == 0 then
            call BT.apply(tower, U, 0)
            if U.getSize() < SIZE_BOSS then
                call CD.apply(tower, U, 0)
            else
                call CD.applyOnlyTimed(tower, U, -1)
            endif
        endif
    endfunction
    
    function periodicDmg takes Buff B returns nothing
        call B.getCaster().doSpellDamage(B.getBuffedUnit(), 4500, B.getCaster().calcSpellCritNoBonus())
    endfunction
    
    //Do not remove or rename this function!
    //Put your initialization tasks here, this function will be called on map init
    private function init takes nothing returns nothing
        set BT = BuffType.createDuplicate(cb_stun, 1.8, 0.00, false)
        call BT.addPeriodicEvent(periodicDmg, 1.0)
        call BT.setBuffIcon('@@1@@')
        
        set CD = BuffType.create(4.8, 0.00, false)
        
        set C = Cast.create('@@0@@', "blizzard", 4.0)
        call C.setDamageEvent(overgrowth_dmg)
    endfunction

On Damage

function onDamage takes Item itm returns nothing
    local Creep target = Event.getTarget()
    local Tower tower = itm.getCarrier()
    if Event.isMainTarget() and tower.calcChance(tower.getBaseAttackspeed()*0.06) then
        call C.pointCastFromTargetOnTarget( tower, target, 1.0, 1.0 )
        call Effect.createColored( "Abilities\\Spells\\NightElf\\EntangleMine\\Roots.mdl", target.getX(), target.getY(), 0.0, 270.0, 1.2, 210, 255, 180, 255 ).setLifetime( 2.5 )
    endif 
endfunction