What is the Chain?

In Riftbound: the League of Legends trading card game, a spell does not take effect the moment you play it. It first waits in a shared zone called the Chain, and while it waits, every player gets a chance to answer it. The Chain is what lets you save a unit from a removal spell, counter a spell before it does anything, or answer an answer. Players who know Magic: The Gathering will recognize it as the stack.

Where is the Chain, and what goes on it?

The Chain is one of the zones off the board, and the whole table shares it. It exists only while a card or an ability is being played, there is never more than one at a time, and anything played while it exists joins it. Everything on the Chain is public, so you always know what you are answering.

• Spells stay on the Chain until they resolve. Their text is then carried out, and the card goes to its owner's trash.
• Units and gear pass through the Chain but leave it as soon as they have been played and enter the board at once, so nobody can answer the card itself.
• Activated abilities, written as a cost, a colon and an effect, stay on the Chain until they resolve, like spells.
• Triggered abilities, which are written with a word such as "when" or "at", as in "At the start of your turn", go on the Chain as soon as their condition is met, on any player's turn.
• Abilities that add Energy or Power, such as the two abilities of every rune, resolve the moment they are used and cannot be answered.

Moving a unit and hiding a card facedown never use the Chain, so neither can be answered. Playing a hidden card later does open a Chain, like any other play.

What can be played while something is on the Chain?

While anything is on the Chain, players can play only cards and abilities with Reaction, and triggered abilities still join it whenever their condition is met. The Core Rules call this a Closed State, and the turn is back in an Open State once the Chain is empty. Action is not enough: it lets a card be played during a showdown, but not while a spell waits to resolve.

Reaction works on any player's turn, so it is your way to act during your opponent's turn even outside a showdown. A hidden card gains Reaction from the turn after it was hidden, so a facedown card can answer the Chain too.

In what order does the Chain resolve?

The newest item on the Chain resolves first, and the item that started the Chain resolves last. A Reaction is played after the spell it answers, so it resolves before that spell. The right to act on the Chain is called Priority in the Core Rules, and it moves in a fixed order.

1. The player who started the Chain gets Priority first. They may add a Reaction of their own, or pass.
2. Priority passes to the next player in turn order, who may play a Reaction or pass, and so on around the table.
3. When every player has passed in a row without adding anything, the newest item resolves.
4. If anything is left, the player who controls the newest remaining item gets Priority, and the round starts again.

So the players get a fresh chance to answer after each item resolves, not just once per Chain. An item always resolves in full before anything else happens, and abilities it triggers are dealt with once it has finished. At tournaments, the Tournament Rules assume that a player who puts a spell or ability on the Chain passes Priority straight away, unless they say they want to keep it.

What does a Chain look like in a game?

Take a one-on-one game in which your opponent has a unit at a battlefield. You play Void Seeker, a Fury spell with Action that deals 4 to a unit at a battlefield and draws you a card, and you choose their unit.

1. Your opponent answers with Flash, a Chaos Reaction from Proving Grounds that moves up to two of their units to base. Flash goes on the Chain above Void Seeker.
2. Both players pass, so Flash resolves first and the unit moves to base.
3. Void Seeker is now the newest item, so you get Priority again. Both players pass, and Void Seeker resolves.
4. The unit is no longer at a battlefield, so it is no longer a legal target and takes no damage. The rest of the spell still happens, and you draw a card.

The Chain could have gone deeper. In a Fury and Calm deck, such as one led by Akali's Legend Rogue Assassin, you could answer Flash with Defy, a Calm Reaction that counters a spell costing no more than 4 Energy and 1 Power. Defy would resolve first and counter Flash, and Void Seeker would then hit a unit that never left. Had your opponent played Wind Wall, which counters any spell, Void Seeker would have done nothing.

What happens to a card that is countered?

A countered card or ability does nothing at all. A countered card goes from the Chain to the trash, the Energy and Power paid for it are not given back, and it does not count as played for abilities that trigger when a card is played. Players can counter something only when a card tells them to, and each such card says what it can counter.

Can you answer a unit when it is played?

You cannot stop the unit itself, but you can often stop what it does. A unit enters the board before anyone gets Priority, so no Reaction can keep it from arriving. An ability that begins "When you play me" is a triggered ability, though, and it goes on the Chain once the unit is on the board, where it can be answered like a spell.

Riptide Rex, a Mind unit, deals 6 to an enemy unit at a battlefield when you play it. Your opponent can answer that ability with Not So Fast, a Calm Reaction from Spiritforged that counters an enemy spell or ability choosing one of their own units or gear. The damage is canceled, and Riptide Rex stays on the board. Flash works too, because a unit moved to base is out of reach. Against Harnessed Dragon, which kills an enemy unit anywhere when you play it, only the counter helps.

How does the Chain work during a showdown?

During a showdown, each card or ability played by the player with Focus starts a Chain of its own, which every player can answer with Reactions. When that Chain has resolved, Focus passes to the next player. A Chain started by a triggered ability, or by an ability that adds Energy or Power, leaves Focus where it was. So when a combat begins, the attacker's triggered abilities go on the Chain first and the defender's last, the defender's resolve first, and Focus is still with the attacker afterwards.

Because only a Reaction can answer a card on the Chain, it helps to know which cards carry one: the spells page lists every spell, and the article on when you can play a spell shows which moments each kind allows. The abilities that wait on the Chain, from triggers to activated abilities, are set out in how card abilities work. The full wording is in the Core Rules on Riot's Rules Hub, from rule 327 on.