Common Patterns

Many scripts repeat the same shapes.

Filters

function s.filter(c)
  return c:IsFaceup() and c:IsSetCard(0x123)
end

Filters usually receive a Card first and return true or false.

Target Then Operation

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

function s.operation(e,tp,eg,ep,ev,re,r,rp)
  Duel.Draw(tp,1,REASON_EFFECT)
end

The target checks legality and declares what will happen. The operation performs the effect.

Flag Effects

Use Flag effects when a script needs temporary memory, such as whether a player has already used one option this turn or whether a specific card was marked by an earlier operation.

Count Limits

Use count limits for normal once-per-turn and shared-use limits. SetCountLimit(1,id) spends a use of the effect's shared count code, while custom activity counters handle restrictions based on Summons, attacks, or chains that already happened this turn.