Set

Set is the act of placing a card (Monster, Spell or Trap card) on the field face-down.

Setting a Monster Card

This is what a set face-down monster looks like

When you set a Monster Card, you place it in a Monster Card Zone horizontally and face-down. If the monster is Level 5 or 6 you must Tribute another monster first and then Set the Level 5 or 6 Monster Card (you can't show your opponent the card you Set). If the card has a higher Level (7+), the same procedure applies, but you must Tribute 2 Monster Cards from your side of the field first (unless there is a specific Tribute requirement). You can only set one monster per turn without the effect of another card just as you can only normal summon once per turn without the effect of another card. Also, if you set a monster, you must wait until your next Main Phase 1 to flip it face up unless the card says otherwise. No monsters require 3 Tributes to be set on the field except "Wicked Gods".

Monsters may only be in face-down attack position by the effect of a card such as "Darkness Approaches". That monster card is face-down and is placed vertically.

Setting a Spell or Trap Card

This is what a set face-down spell or trap looks like

When you Set a Spell/Trap Card, you place it on the field vertically and face-down in a Spell & Trap Card Zone. You can activate any type of Spell Cards in the same turn they are Set except Quick-Play Spell Cards. Trap Cards also can't be activated in the same turn they were Set except by a card effect, such as "Temple of the Kings", "Night Wing Sorceress" (for "Assault Mode Activate" only).