Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Must be Special Summoned with "Mask Change". If this card is Special Summoned: You can target 1 face-up monster your opponent controls; its ATK becomes half its current ATK. Once per turn (Quick Effect): You can pay 500 LP, then target 1 Spell/Trap your opponent controls; return it to the hand.
--M・HERO ブラスト
--Masked HERO Blast
local s,id=GetID()
function s.initial_effect(c)
	c:EnableReviveLimit()
	--Special summon condition
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_SINGLE)
	e1:SetCode(EFFECT_SPSUMMON_CONDITION)
	e1:SetProperty(EFFECT_FLAG_UNCOPYABLE+EFFECT_FLAG_CANNOT_DISABLE)
	c:RegisterEffect(e1)
	--ATK increase
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,0))
	e2:SetCategory(CATEGORY_ATKCHANGE)
	e2:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_O)
	e2:SetCode(EVENT_SPSUMMON_SUCCESS)
	e2:SetProperty(EFFECT_FLAG_CARD_TARGET+EFFECT_FLAG_DAMAGE_STEP+EFFECT_FLAG_DELAY)
	e2:SetTarget(s.atktg)
	e2:SetOperation(s.atkop)
	c:RegisterEffect(e2)
	--Return target to the hand
	local e3=Effect.CreateEffect(c)
	e3:SetDescription(aux.Stringid(id,1))
	e3:SetCategory(CATEGORY_TOHAND)
	e3:SetType(EFFECT_TYPE_QUICK_O)
	e3:SetCode(EVENT_FREE_CHAIN)
	e3:SetRange(LOCATION_MZONE)
	e3:SetProperty(EFFECT_FLAG_CARD_TARGET)
	e3:SetCountLimit(1)
	e3:SetCost(Cost.PayLP(500))
	e3:SetTarget(s.thtg)
	e3:SetOperation(s.thop)
	c:RegisterEffect(e3)
end
function s.atktg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsLocation(LOCATION_MZONE) and chkc:IsControler(1-tp) and chkc:IsFaceup() end
	if chk==0 then return Duel.IsExistingTarget(Card.IsFaceup,tp,0,LOCATION_MZONE,1,nil) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_FACEUP)
	Duel.SelectTarget(tp,Card.IsFaceup,tp,0,LOCATION_MZONE,1,1,nil)
end
function s.atkop(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc and tc:IsFaceup() and tc:IsRelateToEffect(e) then
		local e1=Effect.CreateEffect(e:GetHandler())
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_SET_ATTACK_FINAL)
		e1:SetValue(tc:GetAttack()/2)
		e1:SetReset(RESET_EVENT|RESETS_STANDARD)
		tc:RegisterEffect(e1)
	end
end
function s.thfilter(c)
	return c:IsSpellTrap() and c:IsAbleToHand()
end
function s.thtg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsOnField() and chkc:IsControler(1-tp) and s.thfilter(chkc) end
	if chk==0 then return Duel.IsExistingTarget(s.thfilter,tp,0,LOCATION_ONFIELD,1,nil) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_RTOHAND)
	local g=Duel.SelectTarget(tp,s.thfilter,tp,0,LOCATION_ONFIELD,1,1,nil)
	Duel.SetOperationInfo(0,CATEGORY_TOHAND,g,1,0,0)
end
function s.thop(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc and tc:IsRelateToEffect(e) then
		Duel.SendtoHand(tc,nil,REASON_EFFECT)
	end
end