The chain

Three earlier lessons have already touched the chain. The board and its zones placed it among the zones, Paying a cost moved a card onto it as the first step of playing it, and The combat showdown said that playing a card in a showdown starts one. This track is about what happens while a chain exists.

A zone that comes and goes

The chain is a Non-Board Zone that temporarily exists whenever a card is played or an ability is activated.¹Rule 328. The Chain is a Non-Board Zone that temporarily exists whenever a card is played or an ability is activated. Open in the rules browser Cards and abilities on the chain are Public Information, the level of privacy Runes on the board described.²Rule 108.1.b. Cards and abilities on the Chain are Public Information. Open in the rules browser

The chain exists for as long as a card or ability is on it³Rule 330. The Chain exists as long as a Chain Item is on it. Open in the rules browser, and only one chain can exist at a time.⁴Rule 330.1. Only one Chain can exist at a time. Open in the rules browser If a card begins to be played while a chain already exists, it is placed on that existing chain.⁵Rule 330.2. If a card or token would begin to be played while a Chain already exists, it is placed on the existing Chain. Open in the rules browser

The Closed State from Track 3 is the turn while a chain exists. Its opposite is new here: the turn is in an Open State whenever no chain exists.⁶Rule 309.2. If no Chain exists, the turn is in an Open State. Open in the rules browser If no chain exists yet, the switch happens at the very start of playing. Moving the card to the chain, step 1 of the process, closes the state⁷Rule 354.1. This Closes the State. See rule 307. States of the Turn for more information. Open in the rules browser, and adding an ability that is being activated or triggered creates a Closed State too, even though no card represents it.⁸Rule 401.1. Add a Pending Item to the chain representing the Ability that is either being Activated or Triggered. Notably, although this Chain Item will not have a card representing it, this will create a Closed State. See rule 349. Playing Cards for more information. Open in the rules browser

Pending, then Finalized

Cards and abilities are added to the chain as chain items, which start out Pending and become Finalized.⁹Rule 329. Cards, tokens, and abilities added to the chain are added as Pending Chain Items that become Finalized Chain Items. Open in the rules browser A Pending item is already on the chain.¹⁰Rule 329.1. Pending Items are on the Chain. Open in the rules browser A card is Pending when it first starts being played,¹¹Rule 352.1. When initially being played cards are Pending, as Pending Chain Items. Open in the rules browser and near the end of that process it stops being Pending and becomes a Finalized chain item.¹²Rule 352.2. Near the end of the process cards will cease being Pending and become Finalized Chain Items. Open in the rules browser

So the chain exists, and the turn is in a Closed State, from the moment the card moves there, before its cost is paid.

When a chain item resolves, its game effects are executed in their entirety.¹³Rule 340.1. The newest Finalized Chain Item resolves. Execute its game effects in their entirety. See rule 349. Playing Cards for more information on resolving spells. See rule 398. Playing or Activating Abilities for more information on resolving abilities. Open in the rules browser Which item resolves, and when, is the subject of the third lesson of this track.

What finalizing leaves behind

What happens once a card is no longer Pending depends on what it is. A spell lingers on the chain¹⁴Rule 359.3. A Spell lingers on the Chain. Open in the rules browser as a Finalized chain item,¹⁵Rule 359.3.a. This card becomes a Finalized Chain Item. Open in the rules browser and other players have an opportunity to play Reactions before it resolves.¹⁶Rule 359.3.c. Other players have an opportunity to play Reactions before the resolution of spells. See rule 327. Chains for more information. Open in the rules browser A permanent does not wait: it leaves the chain and becomes a game object,¹⁷Rule 359.2. A Permanent leaves the Chain and becomes a Game Object. Open in the rules browser which is how the unit in Track 2 ended up on the board.

Abilities follow the spell's pattern, with one exception. An ability that finishes the steps of playing becomes a Finalized chain item just like a spell.¹⁸Rule 400.1. When an Ability finishes the steps of playing it becomes a Finalized Chain Item just like a Spell. Open in the rules browser But an ability that adds resources, such as the one a rune uses to add Energy, resolves as soon as it is finalized.¹⁹Rule 429.2. Triggered and activated abilities that Add resources resolve as soon as they are finalized. Open in the rules browser The exception belongs to abilities alone. A spell that adds resources still lingers on the chain as normal.²⁰Rule 429.2.b. Spells that Add resources will linger on the chain as normal when they are finalized. Open in the rules browser