0006: Mana

Status: Accepted

Context

The prototype records mana sources only as tapped. It does not record what mana was produced, what it paid for, or the side effects of producing it. In the prototype's example, PlayerA's life drops from 20 to 19 when Sowing Mycospawn is cast. The cause was Talisman of Impulse's "deals 1 damage to you", but the file cannot show that.

Mana choices decide games: tapping the wrong sources can leave a player unable to cast a spell later in the turn. A replay has to show which source produced which mana and what it was spent on, or it cannot be used to judge whether mana was tapped optimally.

Decision

The full mana trail is recorded.

1. Mana abilities have instance IDs, like every other ability (decision 0003), with kind mana, the source's rules text, and a link to their source. They never go on the stack, but they have costs and effects that need a cause.
2. The costs of a mana ability are attributed to it (by cost:#N), like any other cost (decision 0005).
3. Adding mana is an event naming the player, the mana in CR mana symbols ({W}, {U}, {B}, {R}, {G}, {C}, and so on), and the cause.
4. Spending mana is a cost event naming the mana spent and the spell or ability it paid for (by cost:#N).
5. Other effects of a mana ability are ordinary events caused by it, for example Talisman of Impulse's damage.
6. Unspent mana lost when the pool empties is recorded with a rule cause, only when there was unspent mana.
7. Restricted or special mana keeps its restriction, recorded on the event that adds it.

Illustrative only; exact syntax is defined in the spec:

#50 mana ability of Talisman of Impulse #1: "{T}: Add {R} or {G}. Talisman of Impulse deals 1 damage to you."
Talisman of Impulse #1: tapped by cost:#50
PlayerA adds {G} by #50
#1 deals 1 damage to PlayerA by #50
PlayerA: life 20 -> 19 by #50
PlayerA pays {3}{G}{G} by cost:#2

Rules basis

Checked against the Comprehensive Rules effective 2026-09-25.

• 106.3: mana is produced by the effects of mana abilities (and by some spells and other abilities). "If mana is produced by an ability, the source of that mana is the source of that ability." Each addition has a cause and a source.
• 106.4: mana goes into the player's mana pool, can be spent immediately or later, and "each player's mana pool empties at the end of each step and phase, and the player is said to lose this mana". Adding, spending, and losing are separate events.
• 106.6: some mana restricts how it can be spent or has extra effects when spent. The restriction belongs to the added mana.
• 107.4: mana symbols are the CR's notation for mana and are used as-is.
• 601.2g, 601.2h: mana abilities are activated before costs are paid, and then the total cost is paid. Spending is part of paying the cost.
• 605.3b: an activated mana ability "doesn't go on the stack" and resolves immediately. Its instance ID is not a stack position.
• 120.3a: "Damage dealt to a player by a source without infect causes that player to lose that much life." 119.3: life gain and loss adjust the life total. Damage and the resulting life change are separate events, both caused by the mana ability.

Alternatives rejected

• Taps and totals only (record what was tapped and what was paid, without mana abilities or pool events). Rejected: loses which source made which mana, so a replay cannot show whether mana was tapped optimally, and side effects such as Talisman damage have no cause.
• Mana abilities without instance IDs, using the source permanent as the cause. Rejected: costs and effects of the ability could not be told apart from other effects of the same permanent, and abilities would no longer all work the same way.

Consequences

• Files are noticeably longer on mana-heavy turns: about three lines per mana source tapped.
• The spec must define the add, spend, and lose events, the mana symbol grammar, and the rule cause for the pool emptying.
• Decision 0003 is extended: mana abilities have instance IDs even though they never go on the stack.