Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
There can only be 1 "Earthbound Immortal" monster on the field. If there is no face-up Field Spell on the field, destroy this card. Your opponent's monsters cannot target this card for attacks. This card can attack directly. If this face-up card leaves the field, except by its own effect: Destroy as many face-up monsters your opponent controls as possible, and if you do, inflict 800 damage to your opponent for each monster destroyed.
--地縛神 Aslla piscu
--Earthbound Immortal Aslla piscu
local s,id=GetID()
function s.initial_effect(c)
	--There can only be 1 "Earthbound Immortal" on the field
	c:SetUniqueOnField(1,1,aux.FilterBoolFunction(Card.IsSetCard,SET_EARTHBOUND_IMMORTAL),LOCATION_MZONE)
	--Destroy it if no face-up Field Spell is on the field
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_SINGLE)
	e1:SetProperty(EFFECT_FLAG_SINGLE_RANGE)
	e1:SetRange(LOCATION_MZONE)
	e1:SetCode(EFFECT_SELF_DESTROY)
	e1:SetCondition(s.sdcon)
	c:RegisterEffect(e1)
	--Cannot be targeted for attacks
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_SINGLE)
	e2:SetCode(EFFECT_CANNOT_BE_BATTLE_TARGET)
	e2:SetProperty(EFFECT_FLAG_SINGLE_RANGE)
	e2:SetRange(LOCATION_MZONE)
	e2:SetValue(aux.imval2)
	c:RegisterEffect(e2)
	--Can attack directly
	local e3=Effect.CreateEffect(c)
	e3:SetType(EFFECT_TYPE_SINGLE)
	e3:SetCode(EFFECT_DIRECT_ATTACK)
	c:RegisterEffect(e3)
	--Destroy face-up monsters and inflict damage to the opponent
	local e4=Effect.CreateEffect(c)
	e4:SetDescription(aux.Stringid(id,0))
	e4:SetCategory(CATEGORY_DESTROY+CATEGORY_DAMAGE)
	e4:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_F)
	e4:SetCode(EVENT_LEAVE_FIELD)
	e4:SetCondition(s.descon)
	e4:SetTarget(s.destg)
	e4:SetOperation(s.desop)
	c:RegisterEffect(e4)
end
s.listed_series={SET_EARTHBOUND_IMMORTAL}
function s.sdcon(e)
	local c=e:GetHandler()
	if c:IsStatus(STATUS_BATTLE_DESTROYED) then return false end
	return not Duel.IsExistingMatchingCard(Card.IsFaceup,0,LOCATION_FZONE,LOCATION_FZONE,1,nil)
end
function s.descon(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	return c:IsPreviousPosition(POS_FACEUP) and not c:IsLocation(LOCATION_DECK)
		and (not re or re:GetOwner()~=c)
end
function s.destg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return true end
	local g=Duel.GetMatchingGroup(Card.IsFaceup,tp,0,LOCATION_MZONE,nil)
	Duel.SetOperationInfo(0,CATEGORY_DESTROY,g,#g,0,0)
	if #g~=0 then
		Duel.SetOperationInfo(0,CATEGORY_DAMAGE,nil,0,1-tp,#g*800)
	end
end
function s.desop(e,tp,eg,ep,ev,re,r,rp)
	local g=Duel.GetMatchingGroup(Card.IsFaceup,tp,0,LOCATION_MZONE,nil)
	local ct=Duel.Destroy(g,REASON_EFFECT)
	if ct~=0 then
		Duel.Damage(1-tp,ct*800,REASON_EFFECT)
	end
end