Runes, Energy, Power and the Rune Pool

Costs are mostly paid with two resources. Energy pays the number in a card's cost and has no domain. Power pays the domain-coloured part of a cost and does have a domain, which is usually the domain of the rune that produced it, although some Power is Universal and pays for a cost of any domain (rule 163.1, rule 163.1.a, rule 163.2, rule 163.2.a and rule 163.2.b). Runes are what produce both. A rune is a card type of its own that lives in the 12-card Rune Deck, kept apart from the Main Deck, and a rune on the board is not a Permanent (rule 161, rule 161.1.a, rule 161.2, rule 103.4.a and rule 103.4.b). When a card's text says "card" it means a Main Deck card, so runes are not cards for the effects of game objects, even though they are cards for the purposes of the rules (rule 052).

The usual mistake is to treat a ready rune as if it were already a resource. It is not: you have nothing to spend until you Add it. Every Basic Rune carries two Reaction abilities, one that exhausts the rune to Add 1 Energy and one that recycles it to Add 1 Power of its own domain (rule 164.2.a, rule 164.2.b and rule 164.2.b.1). Added resources go into your Rune Pool, a conceptual collection with no physical marker, and Paying a cost removes them from it (rule 166, rule 166.1, rule 166.3, rule 445.1 and rule 445.1.a). What is left unspent is lost when any player's Main Phase starts and when any turn ends (rule 167 and rule 167.1).

Here is a worked example. Mira has five ready runes, three Fury and two Calm, and wants to play a unit that costs 3 Energy and 1 Fury Power. She exhausts three runes to Add 3 Energy, then recycles one Fury rune to Add 1 Fury Power. The pool holds exactly the cost, and paying it empties the pool. The recycled rune goes to the bottom of her Rune Deck, not to her Main Deck or her trash (rule 417.1.b), so she will not channel it again until the rest of her Rune Deck has been channeled, but the exhausted runes simply ready in her next Awaken Phase (rule 315.1.b). The Calm Power she could have recycled for would not have paid the Fury part of the cost.

Add abilities are special in two ways. They finalize and resolve at once, even in the middle of a task or the resolution of something else, and they do not pass Priority or Focus (rule 430.2 and rule 430.2.a). And a Reaction Add ability can be activated at any moment you have to pay, including while paying a card's cost (rule 430.3, rule 357.1.a and rule 445.2.c). If you decline to Pay something you were instructed to pay, the instruction is negated, and when it was part of playing a card that play is undone (rule 445.2, rule 445.2.a and rule 358.5).

Channeling is how runes reach the board. You take them from the top of the Rune Deck and, unless the effect says otherwise, they arrive ready (rule 431.1 and rule 431.2.a). Each Channel Phase you channel 2, or as many as the Rune Deck still holds (rule 315.3.b, rule 315.3.b.1 and rule 431.3). In a 1v1 game the player going second channels one extra rune in their first Channel Phase (rule 487.7 and rule 488.7).

At a tournament you must keep unspent Energy and Power visible with dice or counters, though resources you spend at once only need to be announced (TR 415.4 and TR 415.4.a). Channeling the wrong number of runes is a game play error. Channeling too many is a Warning, and the extra runes are shuffled back into the Rune Deck if caught within a full round cycle (TR 702.6 and TR 702.6.b.2). Channeling too few is no penalty, and the player channels the missing runes if no more than a full round cycle has passed (TR 702.7 and TR 702.7.b.1), unless forgetting was advantageous, which makes it a Warning (TR 702.7.c).