Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Once per turn during your opponent's Standby Phase, you can remove from play any number of DARK monsters from your Graveyard. This monster gains 500 DEF for each monster you removed, until the End Phase.
--邪狂神の使い
--Maniacal Servant
local s,id=GetID()
function s.initial_effect(c)
	--atk up
	local e1=Effect.CreateEffect(c)
	e1:SetDescription(aux.Stringid(id,0))
	e1:SetCategory(CATEGORY_ATKCHANGE)
	e1:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_O)
	e1:SetRange(LOCATION_MZONE)
	e1:SetCode(EVENT_PHASE|PHASE_STANDBY)
	e1:SetCountLimit(1)
	e1:SetCondition(s.atkcon)
	e1:SetCost(s.atkcost)
	e1:SetOperation(s.atkop)
	c:RegisterEffect(e1)
end
function s.atkcon(e,tp,eg,ep,ev,re,r,rp)
	return Duel.IsTurnPlayer(1-tp)
end
function s.filter(c)
	return c:IsAttribute(ATTRIBUTE_DARK) and c:IsAbleToRemoveAsCost() and aux.SpElimFilter(c,true)
end
function s.atkcost(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return Duel.IsExistingMatchingCard(s.filter,tp,LOCATION_MZONE|LOCATION_GRAVE,0,1,nil) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_REMOVE)
	local g=Duel.SelectMatchingCard(tp,s.filter,tp,LOCATION_MZONE|LOCATION_GRAVE,0,1,99,nil)
	e:SetLabel(#g)
	Duel.Remove(g,POS_FACEUP,REASON_COST)
end
function s.atkop(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	if c:IsRelateToEffect(e) and c:IsFaceup() then
		local e1=Effect.CreateEffect(c)
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_UPDATE_DEFENSE)
		e1:SetValue(e:GetLabel()*500)
		e1:SetReset(RESETS_STANDARD_PHASE_END)
		c:RegisterEffect(e1)
	end
end