Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
If your opponent controls a monster and you control no monsters, you can Special Summon this card (from your hand). During each End Phase: You take 500 damage. This card must be face-up on the field to activate and to resolve this effect.
--ギラギランサー
--Gillagillancer
local s,id=GetID()
function s.initial_effect(c)
	--special summon
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_FIELD)
	e1:SetCode(EFFECT_SPSUMMON_PROC)
	e1:SetProperty(EFFECT_FLAG_UNCOPYABLE)
	e1:SetRange(LOCATION_HAND)
	e1:SetCondition(s.spcon)
	c:RegisterEffect(e1)
	--damage
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,0))
	e2:SetCategory(CATEGORY_DAMAGE)
	e2:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_F)
	e2:SetCode(EVENT_PHASE+PHASE_END)
	e2:SetRange(LOCATION_MZONE)
	e2:SetCountLimit(1)
	e2:SetTarget(s.damtg)
	e2:SetOperation(s.damop)
	c:RegisterEffect(e2)
end
function s.spcon(e,c)
	if c==nil then return true end
	return Duel.GetFieldGroupCount(c:GetControler(),LOCATION_MZONE,0)==0
		and Duel.GetFieldGroupCount(c:GetControler(),0,LOCATION_MZONE)>0
		and Duel.GetLocationCount(c:GetControler(),LOCATION_MZONE)>0
end
function s.damtg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return true end
	Duel.SetTargetPlayer(tp)
	Duel.SetTargetParam(500)
	Duel.SetOperationInfo(0,CATEGORY_DAMAGE,nil,0,tp,500)
end
function s.damop(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	if c:IsRelateToEffect(e) and c:IsFaceup() then
		local p,d=Duel.GetChainInfo(0,CHAININFO_TARGET_PLAYER,CHAININFO_TARGET_PARAM)
		Duel.Damage(p,d,REASON_EFFECT)
	end
end