Summoning mechanics are rules related to Summoning a monster. Nomi, Semi-Nomi, Special Summon, Flip Summon, and Normal Summon and Normal Set (also Tribute Summon and Tribute Setting) are all considered Summoning mechanics. These are Summoning actions that may be negated through a card effect, but, due to being an action of the game itself, do not start a chain.
"Nomi" （「のみ」） is a special term that refers to some monsters. If a monster is a "nomi monster", then it means that the monster cannot be Normal Summoned or Set. It can neither be Special Summoned except by fulfilling a special requirement. Examples of Nomi monsters include "Armed Dragon LV10", "Doom Dozer", and "Raviel, Lord of Phantasms". You can identify a nomi monster because it will have, "This card cannot be Normal Summoned or Set. This card cannot be Special Summoned except by. " in its text. It is also to be noted that the Special Summoning of these cards can only be done while the card in question is in the owner's hand unless stated otherwise in card text.
There is also a type of monster called "Semi-Nomi".
"Semi-Nomi" is a term that refers to a special sub-group of monsters. If a monster is a "Semi-Nomi Monster", then it means it must be Special Summoned by its listed effect before it can be Special Summoned by another effect. "Aqua Spirit", "Harpie Lady Sisters", and "Black Luster Soldier - Envoy of the Beginning" are all Semi-Nomi monsters. You can recognize a Semi-Nomi monster because it will have, "This card cannot be Normal Summoned or Set. This card can only be Special Summoned by. " in its text.
Card without the first sentence, such as "Black Luster Soldier - Envoy of the Beginning, the "No Normal Summon or Set" rule still applies.
After a Semi-Nomi monster has been Special Summoned, it can be Special Summoned through other effects. This only lasts as long as the Semi-Nomi monster does not return to the Hand or Deck. As long as the Semi-Nomi monster remains on the field, in the Graveyard, or banished, you can Special Summon it again with other card effects.
Note that Fusion Monsters, Ritual Monsters, Xyz Monsters and Synchro Monsters are treated as Semi-Nomis unless stated otherwise.
There is also a sub-type of monsters called "Nomi".
A Special Summon is a Summon that is performed through the effect of a single card. Special Summons do not use up your 1 Normal Summon for the turn, and can be conducted as many times as possible in a turn and if generally referred to, a monster can be Special Summoned in face up ATK or DEF position, unless indicated by the card. Also, Special Summons can be activated during either player's turn.
"Premature Burial", "Call of the Haunted", "Monster Reborn", "Soul Resurrection", and "Autonomous Action Unit" can all Special Summon monsters from the Graveyard. Thus, you can activate each card (provided you have enough Life Points) and resurrect five monsters, as well as conduct a Tribute Summon or Tribute Set in the same turn.
A Normal Summon can normally be conducted only once per turn. Setting a monster will also take up your Normal Summon for the turn.
Some cards can change the Normal Summoning rules. "Ultimate Offering", for example, allows you to pay 500 Life Points for each extra Normal Summon you wish to perform in a turn. "Double Summon" allows you to Normal Summon twice in one turn.
Only monsters that are Level 4 or lower can be Normal Summoned without Tribute (Tribute Summoning is still considered Normal Summoning, however) unless specifically designated on the card text (Example: "Swift Gaia the Fierce Knight").
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, then Set the Level 5 or 6 Monster Card (you do not need to 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).
When you Set a Spell/Trap Card, you place it on the field vertically and face-down. Quick-Play Spell Cards cannot be activated in the same turn they are Set. However, you can activate any other type of Spell Cards in the same turn they were Set. Trap Cards however, cannot be activated in the same turn they were Set, unless a card's text designates otherwise, such as "Cathedral of Nobles".
Any monster of Level 5 or higher requires a Tribute Summon (Advanced Summon in the OCG, previously Sacrifice Summon). Monsters that are Level 5 or 6 require one monster to be Tributed (called Release in OCG), while monsters of Level 7 or higher require 2 monsters to be Tributed. Some high-level monsters (such as "Moisture Creature") require 3 monsters to be Tributed in order to activate an effect.
Cards like "Mausoleum of the Emperor" can bend the rules of Tribute Summoning by allowing you to pay Life Points instead of Tributing monsters. However, this means the Summon is then considered a Normal Summon and not a Tribute Summon.
Even if the monster is Tribute Set instead of Tribute Summoned, the correct number of Tributes must be offered. So you cannot Set a monster in order to avoid offering a Tribute.
A Tribute Summon is treated exactly as Normal Summon, except a few cards refer specifically to whether or not the card was Tribute Summoned (such as Monarchs). Normally only one Tribute Summon can be conducted in the same turn (exceptions: see "Ultimate Offering" and "Double Summon"). This means you cannot Normal Summon or Set a low Level monster and then Tribute it immediately to Tribute Summon a high Level monster.
Tributing a monster for a Tribute Summon is not considered a Cost. However, similar to paying costs, players cannot respond immediately to the Tribute of a monster, since Tributing does not have a Spell Speed. If the Tribute Summon of the new monster is negated, however, the Tributed monster will not return to the field.
A Tribute Set is treated almost exactly the same as a Tribute Summon: