The Rune Pool

Energy and Power do not go straight from a rune onto a card. They pass through your Rune Pool first, and knowing how long they stay there is what keeps you from losing them.

Adding and paying

Your Rune Pool is a conceptual collection of the Energy and Power you have available to pay costs.¹Rule 166. The Rune Pool is a conceptual collection of a player's available Energy and Power available to pay Costs. Open in the rules browser It is not a place on the table: Energy and Power have no physical marker, although you may use a tracker if you are keeping unspent Energy and Power over the course of your turn.²Rule 166.3. Energy and Power do not have a physical marker or tracker, although players may wish to use a physical tracker if they are retaining unspent Energy and Power over the course of their turn. Open in the rules browser

Adding is putting resources into a player's Rune Pool.³Rule 429.1. Adding is the action of putting resources into a player's Rune Pool. Open in the rules browser When a card adds Energy or Power, it goes into the pool of the player who controls it.⁴Rule 166.1. When a card adds Energy or Power, it is added to the controlling player's Rune Pool. Open in the rules browser Every ability that includes the action "Add" is adding Energy or Power to the pool⁵Rule 168. All Abilities that include the action "Add" are abilities that are adding Energy or Power to the Rune Pool. See rule 429. Add for more information. Open in the rules browser, and both Basic Rune abilities do: exhausting a rune⁶Rule 164.2.a. [E]: [Reaction] — Add [1]. Open in the rules browser adds 1 Energy, and recycling it⁷Rule 164.2.b. Recycle this: [Reaction] — Add [C]. Open in the rules browser adds 1 Power of its Domain.

You must add Energy and Power to your pool before you can spend them to play cards or pay for abilities.⁸Rule 166.2. Players must add Energy and Power to their Rune Pool in order to be able to spend it to play cards or pay for Abilities with costs. Open in the rules browser Paying a resource is removing it from your pool.⁹Rule 444.1. Paying a resource is the act of removing that resource from your Rune Pool. Open in the rules browser So a rune never pays an Energy or Power cost by itself. Its ability adds to your pool, and paying takes from the pool what the cost asks for.

Adding is a Limited Action¹⁰Rule 429.4. Adding is a Limited Action. Open in the rules browser, the kind of action from the first lesson of this track: you may add resources only when a game effect directs you to.¹¹Rule 429.4.a. Players may only Add resources when Game Effects direct them to do so. Open in the rules browser The two Basic Rune abilities are the game effects that do that in a first game.

Both abilities carry the Reaction tag. Reaction is a keyword the Combat track explains; what matters here is one rule about it. An activated ability that adds resources and has the Reaction tag can be activated at any time that spells or abilities require resources be paid, and the rules' own example adds resources before a spell is played as well as during the step that pays for it.¹²Rule 429.3. Activated abilities that Add resources and have the Reaction tag can be activated at any time that spells or abilities require resources be paid.Example: A player can add Energy and Power through any means before initiating the process of playing a spell. After initiating that process, in the Pay Costs step, they may activate Add Reactions to add Energy or Power to pay costs.Example: A player moves two units to a battlefield where their opponent controls a Mageseeker Investigator. Although they have no window of priority, they may activate Add Reactions to pay for the applied cost from Mageseeker Investigator, and those abilities finalize and resolve immediately. Open in the rules browser The next lesson walks through that step.

When the pool empties

Every player's Rune Pool empties at the start of each player's Main Phase and at the end of each player's turn¹³Rule 167. Every player's Rune Pool empties at the start of each player's Main Phase and the end of each player's turn. Open in the rules browser, and any Energy or Power still in it is lost.¹⁴Rule 167.1. Any unspent Energy or Power are lost. Open in the rules browser "Each player's" matters: your pool also empties at the start of your opponent's Main Phase and at the end of your opponent's turn.

The start of the Main Phase empties the pool as its very first task¹⁵Rule 316.3. 1. Each player's Rune Pool empties. Any unspent Energy and Power are lost. See rule 165. Rune Pools for more information. Open in the rules browser, before the effects that happen at the start of the Main Phase take place.¹⁶Rule 316.4. 2. At the start of Main Phase game effects take place. Open in the rules browser Anything added earlier in the turn and not spent is gone by the time the Main Phase begins.

Between those two moments the rules name nothing else that empties the pool. Track 1 advised adding resources just before you spend them. That is advice, not a rule. Adding earlier in the same Main Phase is allowed, and what you add stays available until the pool next empties. The risk is adding something you then do not spend. The Energy or Power is lost when the pool empties, and losing it does not ready a rune you exhausted to make it, or bring back a rune you recycled.