Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
[ Pendulum Effect ] If you have no card in your other Pendulum Zone: You can target 1 monster in your GY that you can place a Spell Counter on; destroy this card, and if you do, Special Summon that monster, and if you do that, place 1 Spell Counter on it. You can only use this effect of "Mythical Beast Medusa" once per turn. ---------------------------------------- [ Monster Effect ] Each time a Spell Card is activated, place 1 Spell Counter on this card when that Spell resolves. Once per turn, during the Battle Phase (Quick Effect): You can remove 2 Spell Counters from your field, then target 1 face-up monster on the field; its ATK/DEF become half its current ATK/DEF until the end of this turn.
--魔導獣 メデューサ
--Mythical Beast Medusa
local s,id=GetID()
function s.initial_effect(c)
	Pendulum.AddProcedure(c)
	c:EnableCounterPermit(COUNTER_SPELL)
	--special summon
	local e1=Effect.CreateEffect(c)
	e1:SetDescription(aux.Stringid(id,0))
	e1:SetCategory(CATEGORY_DESTROY+CATEGORY_SPECIAL_SUMMON)
	e1:SetType(EFFECT_TYPE_IGNITION)
	e1:SetProperty(EFFECT_FLAG_CARD_TARGET)
	e1:SetRange(LOCATION_PZONE)
	e1:SetCountLimit(1,id)
	e1:SetCondition(s.spcon)
	e1:SetTarget(s.sptg)
	e1:SetOperation(s.spop)
	c:RegisterEffect(e1)
	--add counter
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_CONTINUOUS+EFFECT_TYPE_FIELD)
	e2:SetProperty(EFFECT_FLAG_CANNOT_DISABLE)
	e2:SetCode(EVENT_CHAINING)
	e2:SetRange(LOCATION_MZONE)
	e2:SetOperation(aux.chainreg)
	c:RegisterEffect(e2)
	local e3=Effect.CreateEffect(c)
	e3:SetType(EFFECT_TYPE_CONTINUOUS+EFFECT_TYPE_FIELD)
	e3:SetCode(EVENT_CHAIN_SOLVING)
	e3:SetProperty(EFFECT_FLAG_DELAY)
	e3:SetRange(LOCATION_MZONE)
	e3:SetOperation(s.acop)
	c:RegisterEffect(e3)
	--to hand
	local e4=Effect.CreateEffect(c)
	e4:SetDescription(aux.Stringid(id,1))
	e4:SetCategory(CATEGORY_ATKCHANGE+CATEGORY_DEFCHANGE)
	e4:SetType(EFFECT_TYPE_QUICK_O)
	e4:SetProperty(EFFECT_FLAG_CARD_TARGET+EFFECT_FLAG_DAMAGE_STEP)
	e4:SetCode(EVENT_FREE_CHAIN)
	e4:SetRange(LOCATION_MZONE)
	e4:SetCountLimit(1)
	e4:SetHintTiming(TIMING_DAMAGE_STEP)
	e4:SetCondition(s.atkcon)
	e4:SetCost(s.atkcost)
	e4:SetTarget(s.atktg)
	e4:SetOperation(s.atkop)
	c:RegisterEffect(e4)
end
s.counter_place_list={COUNTER_SPELL}
function s.spcon(e,tp,eg,ep,ev,re,r,rp)
	return Duel.GetFieldGroupCount(tp,LOCATION_PZONE,0) == 1
end
function s.spfilter(c,e,tp)
	return c:IsCanAddCounter(COUNTER_SPELL,1,false,LOCATION_MZONE) and c:IsCanBeSpecialSummoned(e,0,tp,false,false)
end
function s.sptg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	local c=e:GetHandler()
	if chkc then return chkc:IsControler(tp) and chkc:IsLocation(LOCATION_GRAVE) and s.spfilter(chkc,e,tp) end
	if chk==0 then return c:IsDestructable() and Duel.GetLocationCount(tp,LOCATION_MZONE)>0
		and Duel.IsExistingTarget(s.spfilter,tp,LOCATION_GRAVE,0,1,nil,e,tp) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_SPSUMMON)
	local g=Duel.SelectTarget(tp,s.spfilter,tp,LOCATION_GRAVE,0,1,1,nil,e,tp)
	Duel.SetOperationInfo(0,CATEGORY_DESTROY,c,1,0,0)
	Duel.SetOperationInfo(0,CATEGORY_SPECIAL_SUMMON,g,1,0,0)
end
function s.spop(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	if c:IsRelateToEffect(e) and Duel.Destroy(c,REASON_EFFECT)~=0 then
		local tc=Duel.GetFirstTarget()
		if tc:IsRelateToEffect(e) and Duel.SpecialSummon(tc,0,tp,tp,false,false,POS_FACEUP)~=0
			and tc:IsCanAddCounter(COUNTER_SPELL,1) then
			tc:AddCounter(COUNTER_SPELL,1)
		end
	end
end
function s.acop(e,tp,eg,ep,ev,re,r,rp)
	if re:IsHasType(EFFECT_TYPE_ACTIVATE) and re:IsSpellEffect() and e:GetHandler():GetFlagEffect(1)>0 then
		e:GetHandler():AddCounter(COUNTER_SPELL,1)
	end
end
function s.atkcon(e,tp,eg,ep,ev,re,r,rp)
	return Duel.IsBattlePhase() and aux.StatChangeDamageStepCondition()
end
function s.atkcost(e,tp,eg,ep,ev,re,r,rp,chk)
	local c=e:GetHandler()
	if chk==0 then return Duel.IsCanRemoveCounter(tp,1,0,COUNTER_SPELL,2,REASON_COST) end
	Duel.RemoveCounter(tp,1,0,COUNTER_SPELL,2,REASON_COST)
end
function s.atktg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsLocation(LOCATION_MZONE) and chkc:IsFaceup() end
	if chk==0 then return Duel.IsExistingTarget(Card.IsFaceup,tp,LOCATION_MZONE,LOCATION_MZONE,1,nil) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_FACEUP)
	Duel.SelectTarget(tp,Card.IsFaceup,tp,LOCATION_MZONE,LOCATION_MZONE,1,1,nil)
end
function s.atkop(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc:IsRelateToEffect(e) and tc:IsFaceup() then
		local e1=Effect.CreateEffect(e:GetHandler())
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_SET_ATTACK_FINAL)
		e1:SetValue(math.ceil(tc:GetAttack()/2))
		e1:SetReset(RESETS_STANDARD_PHASE_END)
		tc:RegisterEffect(e1)
		local e2=Effect.CreateEffect(e:GetHandler())
		e2:SetType(EFFECT_TYPE_SINGLE)
		e2:SetCode(EFFECT_SET_DEFENSE_FINAL)
		e2:SetValue(math.ceil(tc:GetDefense()/2))
		e2:SetReset(RESETS_STANDARD_PHASE_END)
		tc:RegisterEffect(e2)
	end
end