Spell Speed and chain in Yu-Gi-Oh! Trading Card

In Yu-Gi-Oh! Trading card games, for each monster effect, spell cards and trap cards have certain speed. This can only used when in certain condition and which effect can be chained to another.

Spell Speed

1. Spell Speed 1
   Cards can ordinarily only be played during the turn of the player who controls the card. This is true for Field and Continuous spell cards only when they are initially played. Spell Speed 1 cards cannot be chained to or activated in response to any other card. Spell Speed 1 effects, however, can be chained to other Spell Speed 1 effects.
2. Spell Speed 2
   Cards can be played on either player's turn but must have been set during your turn. Spell Speed 2 cards can be activated in response to any Spell Speed 1 or 2 card or effect. Spell Speed 2 effects are rarer but are usually compulsory to activate.
3. Spell Speed 3
   Cards are only Counter trap cards. They can be activated in response to either Spell Speed 1, 2, or 3.
   

Chaining

A chain is when two or more card effects activate at the same time. The rule of thumb is that a chain resolves backwards in the order of which cards are played. For example:

1. Player 1 plays a Monster Reborn spell card (Spell Speed 1). This spell card allows Player 1 to special summon a monster from either player's graveyard. They choose their opponent's monster, Dark Magician.
2. Player 2 activates a Call of the Haunted continuous trap card (Spell Speed 2). This trap card allows Player 2 to special summon a monster from their own graveyard as long as the trap card remains on the field. They choose their own Dark Magician.

Because Player 2 activated their card last in the chain, their card effect goes first. Player 1 now gets to choose another monster from either player's graveyard to special summon. Most chains are generally only a "Chain link 2", meaning only two cards are activated in a chain. There are longer chains, however:

1. Player 1 plays a Monster Reborn spell card (Spell Speed 1). This spell card allows Player 1 to special summon a monster from either player's graveyard. They choose their opponent's monster, Dark Magician.
2. Player 2 activates a Call of the Haunted continuous trap card (Spell Speed 2). This trap card allows Player 2 to special summon a monster from their own graveyard as long as the trap card remains on the field. They choose their own Dark Magician.
3. Player 1 activates a Royal Decree continuous trap card (Spell Speed 2). This trap card negates the effect of all trap cards on the field except for itself. This means that while player 2 has activated Call of the Haunted and it remains face-up on their side of the field, they are unable to special summon a monster. Because both cards are continuous, unless Royal Decree is immediately destroyed (as part of the same chain), Call of the Haunted will be unable to Special Summon a monster. Note that if Royal Decree were to be destroyed next turn, or even in the next phase of the current turn, this does not mean that Call of the Haunted can Special Summon a monster; the Special Summon is activated upon activation of Call of the Haunted, and Call of the Haunted's activation and effect were negated, and it was not returned face-down, and can not be reactivated.
4. Player 2 activates a Dust Tornado trap card (Spell Speed 2). Dust Tornado destroys one spell or trap card on the field. Player 2 targets the Royal Decree.

Because a chain resolves backwards, the chain would play out like this: Dust Tornado destroys Royal Decree. Because Royal Decree is no longer on the field, the next effect activated is Call of the Haunted, followed by Monster Reborn. Because Dust Tornado was played after Royal Decree, the effect activates first, meaning the effect of Royal Decree never negated Dust Tornado. Q: But does the Monster Reborn work? It was activated, targeting a monster that was not effectively present in the Graveyard.

Main Article: Yu-Gi-Oh! General Rules