Player-Targeted Effects

Some effects do not target a card. They target a player, store an amount, then use that stored player and amount during resolution. Draw, damage, recovery, discard, and many "your opponent" effects use this shape.

This is different from selecting card targets with Duel.SelectTarget. A player target is Chain data, not a Card or Group.

The Basic Shape

Pot of Greed (c55144522.lua) is the cleanest local example:

lua

function s.target(e,tp,eg,ep,ev,re,r,rp,chk)
    if chk==0 then return Duel.IsPlayerCanDraw(tp,2) end
    Duel.SetTargetPlayer(tp)
    Duel.SetTargetParam(2)
    Duel.SetOperationInfo(0,CATEGORY_DRAW,nil,0,tp,2)
end

function s.activate(e,tp,eg,ep,ev,re,r,rp)
    local p,d=Duel.GetChainInfo(0,CHAININFO_TARGET_PLAYER,CHAININFO_TARGET_PARAM)
    Duel.Draw(p,d,REASON_EFFECT)
end

The target branch stores two values:

Function	Stored value
`Duel.SetTargetPlayer`	The player that the operation will affect.
`Duel.SetTargetParam`	A single integer parameter, commonly an amount or count.

The operation reads them with Duel.GetChainInfo. Request the CHAININFO_* fields in the same order you want them returned.

Why Store The Values?

Store player and amount data when the operation should resolve with the values chosen or calculated at activation. That keeps the operation from silently changing its mind later.

Mask of Darkness's old-style draw cousin, Masked Sorcerer (c10189126.lua), sets the player and draw count when battle damage is inflicted:

lua

function s.target(e,tp,eg,ep,ev,re,r,rp,chk)
    if chk==0 then return true end
    Duel.SetTargetPlayer(tp)
    Duel.SetTargetParam(1)
    Duel.SetOperationInfo(0,CATEGORY_DRAW,nil,0,tp,1)
end

function s.operation(e,tp,eg,ep,ev,re,r,rp)
    local p,d=Duel.GetChainInfo(0,CHAININFO_TARGET_PLAYER,CHAININFO_TARGET_PARAM)
    Duel.Draw(p,d,REASON_EFFECT)
end

The operation does not need to recompute who inflicted damage. It uses the Chain data that was stored when the trigger was placed on the Chain.

Player Target Property

Effects that target a player usually set EFFECT_FLAG_PLAYER_TARGET:

lua

local e1=Effect.CreateEffect(c)
e1:SetCategory(CATEGORY_DRAW)
e1:SetType(EFFECT_TYPE_ACTIVATE)
e1:SetProperty(EFFECT_FLAG_PLAYER_TARGET)
e1:SetCode(EVENT_FREE_CHAIN)
e1:SetTarget(s.target)
e1:SetOperation(s.activate)
c:RegisterEffect(e1)

This is a property flag on the effect. It tells the engine and client that the effect's target is a player rather than only cards.

Do not use EFFECT_FLAG_CARD_TARGET for this unless the effect also selects card targets. A player target is not a card target.

Operation Info Still Matters

Duel.SetOperationInfo informs the engine and client what the effect intends to do. For player-targeted draw, damage, and recovery, the last two fields are usually the target player and the amount:

lua

Duel.SetOperationInfo(0,CATEGORY_DRAW,nil,0,tp,2)
Duel.SetOperationInfo(0,CATEGORY_DAMAGE,nil,0,1-tp,1000)
Duel.SetOperationInfo(0,CATEGORY_RECOVER,nil,0,tp,500)

The operation info does not store the values for your Lua operation. Use SetTargetPlayer and SetTargetParam for that. Operation info is metadata; Chain target player/parameter are the values your script reads back.

Damage And Recovery Use The Same Shape

Lava Golem (c102380.lua) deals damage to its controller during that player's Standby Phase:

lua

function s.damtg(e,tp,eg,ep,ev,re,r,rp,chk)
    if chk==0 then return true end
    Duel.SetTargetPlayer(tp)
    Duel.SetTargetParam(1000)
    Duel.SetOperationInfo(0,CATEGORY_DAMAGE,0,0,tp,1000)
end

function s.damop(e,tp,eg,ep,ev,re,r,rp)
    local p,d=Duel.GetChainInfo(0,CHAININFO_TARGET_PLAYER,CHAININFO_TARGET_PARAM)
    Duel.Damage(p,d,REASON_EFFECT)
end

The same pattern appears in recovery effects, except the operation calls Duel.Recover.

When The Amount Is Dynamic

Sometimes the amount is calculated in the target branch:

lua

local ct=Duel.GetMatchingGroupCount(s.filter,tp,LOCATION_GRAVE,0,nil)
if chk==0 then return ct>0 and Duel.IsPlayerCanDraw(tp,ct) end
Duel.SetTargetPlayer(tp)
Duel.SetTargetParam(ct)
Duel.SetOperationInfo(0,CATEGORY_DRAW,nil,0,tp,ct)

That pattern means "draw the number that was legal and announced at activation." If the text says to count again at resolution, do not store the count as the final amount. Store only the player, then recompute the amount in the operation.

Changing Stored Player Data

The local core also exposes Duel.ChangeTargetPlayer and Duel.ChangeTargetParam. They edit already-stored Chain data. Use them only for effects that explicitly change an existing Chain's target player or parameter.

For a normal new effect, use SetTargetPlayer and SetTargetParam in that effect's own target function.

Common Mistakes

Mistake	Better pattern
Selecting no card target but forgetting `EFFECT_FLAG_PLAYER_TARGET`.	Add the player-target property when the effect targets a player.
Reading `tp` in the operation instead of stored Chain data.	Use `Duel.GetChainInfo(0,CHAININFO_TARGET_PLAYER,CHAININFO_TARGET_PARAM)`.
Assuming `SetOperationInfo` stores Lua operation data.	Use `SetTargetPlayer` and `SetTargetParam` for values you read later.
Recomputing an announced amount at resolution by accident.	Store the count with `SetTargetParam` when the amount should be fixed at activation.
Using `EFFECT_FLAG_CARD_TARGET` for a player-only effect.	Reserve card-target flags for real card targets selected through targeting APIs.

The reliable mental model is: target function checks legality, stores player data, announces operation info; operation reads the stored Chain data and applies the effect.

Player-Targeted Effects ​

The Basic Shape ​

Why Store The Values? ​

Player Target Property ​

Operation Info Still Matters ​

Damage And Recovery Use The Same Shape ​

When The Amount Is Dynamic ​

Changing Stored Player Data ​

Common Mistakes ​