Making spell effect appear a few time but not spam

// +------------------------------------------------------------+
// |                                                            |
// |                   -=-=- Knockback -=-=-                    |
// |                    Requires Jass NewGen                    |
// |                                                            |
// +------------------------------------------------------------+
// |                                                            |
// |   Blinks onto a target enemy, dealing damage.              |
// |      After a period of time, your Hero blinks back         |
// |         to their original position, dealing damage in      |
// |            a 450 AoE around where he lands. Casting        |
// |               range improves per level.                    |
// |                                                            |
// +------------------------------------------------------------+
// |                                                            |
// |   -=-=- How To Implement -=-=-                             |
// |      1. Create a trigger named Knockback                   |
// |      2. Copy the text from this map's trigger              |
// |      3. Copy/paste it into your map's Knockback trigger    |
// |      4. Copy all the abilities to your map.                |
// |      5. Copy all the units to your map.                    |
// |      6. Enjoy!                                             |
// |                                                            |
// +------------------------------------------------------------+
// |                                                            |
// |   -=-=- Credits -=-=-                                      |
// |      Credits are not needed, but appreciated               |
// |         Just don't claim this as yours                     |
// |                                                            |
// +------------------------------------------------------------+

scope Knockback initializer KBInit

// +-------------------------------------+
// |       -=-=- MODIFY HERE -=-=-       |
// |       -=-=- MODIFY HERE -=-=-       |
// |       -=-=- MODIFY HERE -=-=-       |
// +-------------------------------------+

    globals
        private constant integer KBID = 'BOLT'       // Rawcode of dummy spell 
        private constant real SLIDE_SPEED = 700       // Slide speed
        private constant string KBEFFECT = "Abilities\\Spells\\Orc\\WarStomp\\WarStompCaster.mdl"       // SFX of the targeted spell unit
        private constant boolean KillTrees = true       // Kill trees or not?
        private constant string BLOOD = "Objects\\Spawnmodels\\Human\\HumanLargeDeathExplode\\HumanLargeDeathExplode.mdl"       // SFX when unit comes within the targeted spell unit who got hit
        private constant real TreeRADIUS = 200       // Range needed for a tree to be beside targeted unit before tree dies
        private constant real UnitRADIUS = 200       // Range needed for a unit to be beside targeted unit before they take damage
        private boolexpr KBDAMGER
    endglobals
    
    private function KBDISTANCES takes integer level returns integer
        return level * 300       // How far the unit will get knocked backed
    endfunction

    private function KBDAMAGE takes integer level returns integer
        return level * 5       // Damage the targeted unit takes
    endfunction

// +------------------------------------------------+
// |       -=-=- DO NOT TOUCH PAST HERE -=-=-       |
// |       -=-=- DO NOT TOUCH PAST HERE -=-=-       |
// |       -=-=- DO NOT TOUCH PAST HERE -=-=-       |
// +------------------------------------------------+

    private function KBConditions takes nothing returns boolean
        return GetSpellAbilityId() == KBID // the ID of dummy spell
    endfunction

    private function KillTree takes nothing returns nothing
        call KillDestructable(GetEnumDestructable())
    endfunction
    
    struct Knock
        unit target
        unit caster
        real x1
        real y1
        real cos
        real sin
        real DISTANCE
        real angle
    endstruct

    private function KBFilters takes nothing returns boolean
        return true 
    endfunction

    private function KBKnockback takes nothing returns boolean
        local Knock data = TT_GetData()
        local unit t
        local real x = GetUnitX(data.target)
        local real y = GetUnitY(data.target)
        local location CasterLoc = GetUnitLoc(data.target)
        //local group g = GetUnitsInRangeOfLocMatching(UnitRADIUS, CasterLoc, DAMGER)
        // Start of what I added
        local group g = CreateGroup()
        call GroupEnumUnitsInRangeOfLoc(g, CasterLoc, UnitRADIUS, KBDAMGER)
        call DestroyBoolExpr(KBDAMGER)
        // End of what I added
        set x = x + data.cos * TT_PERIOD * SLIDE_SPEED
        set y = y + data.sin * TT_PERIOD * SLIDE_SPEED
        loop
        set t = FirstOfGroup(g)
        exitwhen t == null
            call GroupRemoveUnit(g, t)
            if IsUnitEnemy(data.caster, GetOwningPlayer(t)) then
                call UnitDamageTarget(data.caster, t, KBDAMAGE(GetUnitAbilityLevel(data.caster, KBID)), false, false, ATTACK_TYPE_HERO, DAMAGE_TYPE_NORMAL, WEAPON_TYPE_WHOKNOWS)
               call DestroyEffect(AddSpecialEffect(BLOOD,GetUnitX(t),GetUnitY(t)))         endif
        endloop
        if KillTrees == true then
            call EnumDestructablesInCircleBJ(TreeRADIUS, CasterLoc, function KillTree)
        endif
        call SetUnitPosition (data.target, x, y)
        set data.DISTANCE = data.DISTANCE - TT_PERIOD * SLIDE_SPEED
        call RemoveLocation(CasterLoc)
        call DestroyGroup(g)
        set g = null
        set CasterLoc = null
        set t = null
        if data.DISTANCE <= 0 then
            call data.destroy ()
            return true
        endif
        return false
    endfunction

    private function KBActions takes nothing returns nothing
        local Knock data = Knock.create()
        local real x1
        local real y1
        local real x2
        local real y2
        local real angle
        local integer stomp = 7
        set data.caster = GetTriggerUnit()
        set data.target = GetSpellTargetUnit()
        set x1 = GetUnitX (data.caster)
        set y1 = GetUnitY (data.caster)
        set x2 = GetUnitX (data.target)
        set y2 = GetUnitY (data.target)
        set angle = Atan2 (y2 - y1, x2 - x1)
        set data.DISTANCE = KBDISTANCES(GetUnitAbilityLevel(GetTriggerUnit(), KBID))
        set data.cos = Cos (angle)
        set data.sin = Sin (angle)
        call TT_Start (function KBKnockback, data)
        loop
        exitwhen stomp == 0
        call TriggerSleepAction(GetRandomReal(0.1,0.15))
        call DestroyEffect(AddSpecialEffect(KBEFFECT,GetUnitX(data.target),GetUnitY(data.target)))
        set stomp = stomp - 1
        endloop
    endfunction

//===========================================================================
    private function KBInit takes nothing returns nothing
        local trigger t = CreateTrigger()
        call TriggerRegisterAnyUnitEventBJ(t, EVENT_PLAYER_UNIT_SPELL_EFFECT)
        call TriggerAddCondition(t, Condition(function KBConditions))
        call TriggerAddAction(t, function KBActions)
        set KBDAMGER = Filter(function KBFilters)
    endfunction

endscope

call DestroyEffect(AddSpecialEffect(BLOOD,GetUnitX(t),GetUnitY(t)))

if GetRandomInt(1,10) == 1 then
call DestroyEffect(AddSpecialEffect(BLOOD,GetUnitX(t),GetUnitY(t)))
endif

real OneThirdMaximumDist

if(ModuloReal(CurrentDistance, OneThirdMaximumDistance) == 1))then
 //do
endif