Tribute Summon Materials

Tribute Summon scripts sit between ordinary Normal Summons and effect resolution. The engine asks how many Tributes the monster needs, gathers cards that can be Tributed, gives some of those cards a Tribute value, then releases the selected material cards with REASON_SUMMON+REASON_MATERIAL.

This page focuses on cards that are treated as multiple Tributes, such as Egyptian God Slime, and the nearby mechanics that often appear in the same scripts.

Where This Fits

Need	Common tool
A card counts as 2 Tributes for certain Tribute Summons	EFFECT_DOUBLE_TRIBUTE on the card being Tributed.
A card can stand in for a 3-Tribute monster, like Egyptian God Slime	A custom Summon/Set procedure that selects and releases that card.
A monster needs 3 Tributes by rule	EFFECT_LIMIT_SUMMON_PROC with Duel.CheckTribute(c,3) and Duel.SelectTribute(tp,c,3,3).
A monster needs fewer Tributes this turn	EFFECT_DECREASE_TRIBUTE or EFFECT_DECREASE_TRIBUTE_SET.
A monster can only be Tribute Summoned with certain Tributes	EFFECT_TRIBUTE_LIMIT.
A card needs to remember what was Tributed	EFFECT_MATERIAL_CHECK and Card.GetMaterial.

Local constant files also define EFFECT_TRIPLE_TRIBUTE, but it is marked N/A in constant.lua and is commented out in the local core header. The verified MDPro4/YGOPro path for "treated as 3 Tributes" is a custom Summon procedure, not a generic triple-Tribute effect code.

The Core Model

For ordinary Tribute Summons, the core starts from the monster's Level:

Monster Level	Base Tribute requirement
Level 1-4	0 Tributes
Level 5-6	1 Tribute
Level 7 or higher	2 Tributes

Card.GetTributeRequirement returns the current minimum and maximum Tribute counts after reduction effects are considered:

local minc,maxc=c:GetTributeRequirement()

The current maximum can matter. A reduction effect may allow a monster to be Tribute Summoned with fewer Tributes while still allowing the normal number.

When the core builds the Tribute candidate list, each releasable card gets a release_param:

Candidate state	Tribute value used by selection
Ordinary releasable monster	1
A monster affected by EFFECT_DOUBLE_TRIBUTE for the monster being Summoned	2

That is why Duel.GetTributeCount can return a number larger than the size of Duel.GetTributeGroup. The count is a Tribute value total, not just a card count.

Simple Double-Tribute Monsters

Kaiser Sea Horse (c17444133.lua) is the cleanest pattern:

function c17444133.initial_effect(c)
    local e1=Effect.CreateEffect(c)
    e1:SetType(EFFECT_TYPE_SINGLE)
    e1:SetCode(EFFECT_DOUBLE_TRIBUTE)
    e1:SetValue(c17444133.condition)
    c:RegisterEffect(e1)
end

function c17444133.condition(e,c)
    return c:IsAttribute(ATTRIBUTE_LIGHT)
end

The value function receives the monster that would be Tribute Summoned as c. Return true when this card should count as 2 Tributes for that monster.

Double Coston (c44436472.lua) is the DARK version:

function c44436472.condition(e,c)
    return c:IsAttribute(ATTRIBUTE_DARK)
end

The effect is on the card being Tributed, not on the monster being Summoned. The core checks it while building the Tribute list with the target monster as the argument.

Temporary Double-Tribute Effects

The First Monarch (c8522996.lua) becomes a Trap Monster, lets the player declare an Attribute, changes itself to that Attribute, then registers a temporary double-Tribute effect:

local e2=Effect.CreateEffect(c)
e2:SetType(EFFECT_TYPE_SINGLE)
e2:SetCode(EFFECT_DOUBLE_TRIBUTE)
e2:SetProperty(EFFECT_FLAG_CANNOT_DISABLE)
e2:SetValue(c8522996.condition)
e2:SetReset(RESET_EVENT+RESETS_STANDARD)
c:RegisterEffect(e2)

Its condition compares the monster being Tribute Summoned with The First Monarch's current Attribute:

function c8522996.condition(e,c)
    return c:IsAttribute(e:GetHandler():GetAttribute())
end

This is the same mechanic as Kaiser Sea Horse. The difference is duration: the effect is created later and resets when the Trap Monster leaves its valid state.

Egyptian God Slime

Egyptian God Slime (c42166000.lua) is not implemented with EFFECT_TRIPLE_TRIBUTE. The local script gives Egyptian God Slime a marker effect, then registers custom Normal Summon and Set procedures while it is on the field.

First, the marker:

local e0=Effect.CreateEffect(c)
e0:SetType(EFFECT_TYPE_SINGLE)
e0:SetCode(42166000)
c:RegisterEffect(e0)

Then the Summon procedure:

local e3=Effect.CreateEffect(c)
e3:SetDescription(aux.Stringid(42166000,0))
e3:SetType(EFFECT_TYPE_FIELD)
e3:SetCode(EFFECT_LIMIT_SUMMON_PROC)
e3:SetRange(LOCATION_MZONE)
e3:SetTargetRange(LOCATION_HAND,0)
e3:SetCondition(c42166000.ttcon)
e3:SetTarget(c42166000.RequireSummon)
e3:SetOperation(c42166000.ttop)
e3:SetValue(SUMMON_TYPE_ADVANCE)
c:RegisterEffect(e3)

SetTargetRange(LOCATION_HAND,0) means this field procedure applies to monsters in your hand. RequireSummon lists the monsters that may use Egyptian God Slime as the whole 3-Tribute procedure, including the Egyptian Gods:

function c42166000.RequireSummon(e,c)
    return c:IsCode(10000000,10000010,10000020,10000080,21208154,57793869,62180201,57761191)
end

The condition asks whether an Egyptian God Slime marker is available and whether releasing it would open a Monster Zone:

function c42166000.ttfilter(c,tp)
    return c:IsHasEffect(42166000) and c:IsReleasable(REASON_SUMMON)
        and Duel.GetMZoneCount(tp,c)>0
end

function c42166000.ttcon(e,c,minc)
    if c==nil then return true end
    local tp=c:GetControler()
    return minc<=3 and Duel.IsExistingMatchingCard(c42166000.ttfilter,tp,LOCATION_MZONE,0,1,nil,tp)
end

The operation selects exactly one Egyptian God Slime, records it as material, and releases it as Summon material:

function c42166000.ttop(e,tp,eg,ep,ev,re,r,rp,c)
    Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_RELEASE)
    local g=Duel.SelectMatchingCard(tp,c42166000.ttfilter,tp,LOCATION_MZONE,0,1,1,nil,tp)
    c:SetMaterial(g)
    Duel.Release(g,REASON_SUMMON+REASON_MATERIAL)
end

That is the key lesson: "treated as 3 Tributes" is modeled by a custom procedure that replaces the normal 3-Tribute selection for specific monsters. It is not the same as a generic release_param=3 effect.

Egyptian God Slime also has a second custom procedure for monsters that can be Tribute Summoned by Tributing 3 monsters, where one Egyptian God Slime counts as 3 of a larger requirement. That procedure combines an ordinary Duel.SelectTribute selection with one selected Egyptian God Slime, merges the groups, records the material, and releases all of them.

Three-Tribute Monsters

Slifer the Sky Dragon (c10000020.lua) shows the ordinary "this monster needs 3 Tributes" shape:

local e1=Effect.CreateEffect(c)
e1:SetDescription(aux.Stringid(10000020,2))
e1:SetProperty(EFFECT_FLAG_CANNOT_DISABLE+EFFECT_FLAG_UNCOPYABLE)
e1:SetType(EFFECT_TYPE_SINGLE)
e1:SetCode(EFFECT_LIMIT_SUMMON_PROC)
e1:SetCondition(c10000020.ttcon)
e1:SetOperation(c10000020.ttop)
e1:SetValue(SUMMON_TYPE_ADVANCE)
c:RegisterEffect(e1)

The condition and operation use the Tribute APIs directly:

function c10000020.ttcon(e,c,minc)
    if c==nil then return true end
    return minc<=3 and Duel.CheckTribute(c,3)
end

function c10000020.ttop(e,tp,eg,ep,ev,re,r,rp,c)
    local g=Duel.SelectTribute(tp,c,3,3)
    c:SetMaterial(g)
    Duel.Release(g,REASON_SUMMON+REASON_MATERIAL)
end

Use this pattern when the monster itself has a nonstandard Tribute Summon requirement. Use the Egyptian God Slime pattern when another card on the field creates an alternate procedure for that monster.

Reducing Tribute Requirements

Amarylease (c18988391.lua) registers a temporary field effect that reduces the Tribute requirement for monsters in the hand:

local e1=Effect.CreateEffect(e:GetHandler())
e1:SetType(EFFECT_TYPE_FIELD)
e1:SetCode(EFFECT_DECREASE_TRIBUTE)
e1:SetTargetRange(LOCATION_HAND,0)
e1:SetCountLimit(1)
e1:SetValue(0x1)
e1:SetReset(RESET_PHASE+PHASE_END)
Duel.RegisterEffect(e1,tp)

The local core reads the value as a packed number:

Part	Meaning
low 16 bits, value & 0xffff	Amount subtracted from the minimum Tribute count.
high 16 bits, value >> 16	Amount subtracted from the maximum Tribute count.

So 0x1 reduces the minimum by 1 but leaves the maximum alone. A Level 7 monster can become Tribute Summonable with 1 Tribute while still allowing 2.

Simorgh, Bird of Ancestry (c86489182.lua) returns 0x10001,86489182:

function c86489182.decval(e,c)
    return 0x10001,86489182
end

That reduces both minimum and maximum by 1. The second returned value is a duplicate-prevention code; the core uses it so multiple effects with the same code do not stack repeatedly.

Use EFFECT_DECREASE_TRIBUTE_SET for Set procedures. Simorgh, Bird of Ancestry clones the Summon reduction and changes the code for setting:

local e4=e3:Clone()
e4:SetCode(EFFECT_DECREASE_TRIBUTE_SET)
c:RegisterEffect(e4)

Restricting Which Tributes Can Be Used

EFFECT_TRIBUTE_LIMIT belongs on the monster being Tribute Summoned. Its value function receives a potential Tribute and returns true when that Tribute is not allowed.

Simorgh, Bird of Divinity (c14989021.lua) can only use WIND monsters as Tributes:

local e2=Effect.CreateEffect(c)
e2:SetType(EFFECT_TYPE_SINGLE)
e2:SetCode(EFFECT_TRIBUTE_LIMIT)
e2:SetValue(c14989021.tlimit)
c:RegisterEffect(e2)

function c14989021.tlimit(e,c)
    return not c:IsAttribute(ATTRIBUTE_WIND)
end

Read the predicate carefully. Because the function returns not WIND, it is not saying "this is a good Tribute"; it is saying "this candidate is forbidden by the limit."

Remembering Tributed Materials

After a Tribute Summon, scripts can inspect the recorded material group with Card.GetMaterial. The procedure or core must call Card.SetMaterial before the release for this to be useful.

Simorgh, Bird of Ancestry uses EFFECT_MATERIAL_CHECK to remember whether all Tributed monsters were WIND:

local e6=Effect.CreateEffect(c)
e6:SetType(EFFECT_TYPE_SINGLE)
e6:SetCode(EFFECT_MATERIAL_CHECK)
e6:SetValue(c86489182.valcheck)
e6:SetLabelObject(e5)
c:RegisterEffect(e6)

function c86489182.valcheck(e,c)
    local g=c:GetMaterial()
    if g:FilterCount(Card.IsAttribute,nil,ATTRIBUTE_WIND)==#g and #g>0 then
        e:GetLabelObject():SetLabel(1)
    else
        e:GetLabelObject():SetLabel(0)
    end
end

Hardened Armed Dragon (c68473226.lua) shows a different memory pattern. It checks EVENT_BE_PRE_MATERIAL, confirms it was used for a Tribute Summon with r==REASON_SUMMON, then grants protection to the monster that used it as material.

Tribute APIs In Custom Procedures

Use the Tribute APIs when writing a custom Tribute Summon procedure:

Function	Use
Duel.GetTributeGroup	Get the actual candidate cards.
Duel.GetTributeCount	Count available Tribute value, including cards that count as 2 Tributes.
Duel.CheckTribute	Check whether a Tribute selection from min to max exists.
Duel.SelectTribute	Ask the player to choose Tributes for the monster.
Card.SetMaterial	Record selected Tributes as Summon materials.
Duel.Release	Release selected Tributes with REASON_SUMMON+REASON_MATERIAL.

The local define notes for Duel.GetTributeCount explicitly warn that the count may not equal the number of cards in Duel.GetTributeGroup, because some cards can be used as multiple Tributes.

Common Pitfalls

Mistake	Better habit
Using EFFECT_DOUBLE_TRIBUTE on the monster being Tribute Summoned.	Put it on the card that will be Tributed, and make the value function inspect the monster being Summoned.
Treating EFFECT_TRIPLE_TRIBUTE as a usable local mechanic.	Use a custom procedure; locally that constant is N/A and not implemented in the verified core path.
Assuming a double-Tribute card counts as 2 for every release.	The verified core double-Tribute path is Tribute Summon selection. Ordinary costs and effect releases use actual cards unless a script customizes them.
Forgetting Card.SetMaterial before releasing custom Tribute material.	Record the selected group first, then release it with REASON_SUMMON+REASON_MATERIAL.
Confusing a reduced requirement with a larger Tribute value.	EFFECT_DECREASE_TRIBUTE changes what the monster needs; EFFECT_DOUBLE_TRIBUTE changes what a candidate contributes.
Reading EFFECT_TRIBUTE_LIMIT backwards.	Its value function returns true for a forbidden candidate, as shown by Simorgh, Bird of Divinity.
Using Duel.SelectMatchingCard for ordinary Tribute selection.	Use Duel.SelectTribute when you need the core to respect Tribute value, Tribute limits, extra releases, and zone constraints.
Forgetting Set procedures.	Use EFFECT_LIMIT_SET_PROC, EFFECT_SET_PROC, or EFFECT_DECREASE_TRIBUTE_SET when the card text also affects Setting.

Useful API Pages

• Card.GetTributeRequirement
• Card.SetMaterial
• Card.GetMaterial
• Card.IsReleasable
• Card.IsSummonType
• Duel.GetTributeGroup
• Duel.GetTributeCount
• Duel.CheckTribute
• Duel.SelectTribute
• Duel.Release
• Duel.Summon
• Duel.MSet
• Duel.GetMZoneCount
• Duel.GetLocationCount
• Effect.SetValue
• Effect.SetTargetRange
• Effect.SetLabelObject
• Effect.GetLabelObject
• Group.Merge
• Group.CheckSubGroup