Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
You can Special Summon this card by Tributing 1 "Ocean's Keeper". You can discard 1 WATER monster to the Graveyard to destroy 1 face-down card.
--マザー・ブレイン
--Cranium Fish
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)
	e1:SetTarget(s.sptg)
	e1:SetOperation(s.spop)
	c:RegisterEffect(e1)
	--to hand
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,0))
	e2:SetProperty(EFFECT_FLAG_CARD_TARGET)
	e2:SetCategory(CATEGORY_DESTROY)
	e2:SetType(EFFECT_TYPE_IGNITION)
	e2:SetRange(LOCATION_MZONE)
	e2:SetCost(s.descost)
	e2:SetTarget(s.destg)
	e2:SetOperation(s.desop)
	c:RegisterEffect(e2)
end
s.listed_names={45045866}
function s.spcon(e,c)
	if c==nil then return true end
	return Duel.CheckReleaseGroup(c:GetControler(),Card.IsCode,1,false,1,true,c,c:GetControler(),nil,false,nil,45045866)
end
function s.sptg(e,tp,eg,ep,ev,re,r,rp,c)
	local g=Duel.SelectReleaseGroup(tp,Card.IsCode,1,1,false,true,true,c,nil,nil,false,nil,45045866)
	if g then
		g:KeepAlive()
		e:SetLabelObject(g)
	return true
	end
	return false
end
function s.spop(e,tp,eg,ep,ev,re,r,rp,c)
	local g=e:GetLabelObject()
	if not g then return end
	Duel.Release(g,REASON_COST)
	g:DeleteGroup()
end
function s.cfilter(c)
	return c:IsAttribute(ATTRIBUTE_WATER) and c:IsDiscardable() and c:IsAbleToGraveAsCost()
end
function s.descost(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return Duel.IsExistingMatchingCard(s.cfilter,tp,LOCATION_HAND,0,1,nil) end
	Duel.DiscardHand(tp,s.cfilter,1,1,REASON_COST|REASON_DISCARD)
end
function s.filter(c)
	return c:IsFacedown()
end
function s.destg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsOnField() and s.filter(chkc) end
	if chk==0 then return Duel.IsExistingTarget(s.filter,tp,LOCATION_ONFIELD,LOCATION_ONFIELD,1,nil) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_DESTROY)
	local g=Duel.SelectTarget(tp,s.filter,tp,LOCATION_ONFIELD,LOCATION_ONFIELD,1,1,nil)
	Duel.SetOperationInfo(0,CATEGORY_DESTROY,g,1,0,0)
end
function s.desop(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc and tc:IsFacedown() and tc:IsRelateToEffect(e) then
		Duel.Destroy(tc,REASON_EFFECT)
	end
end