For Rek'Sai's legend ability, do you have to pay the full cost of the unit? Also, if Candlelit Sanctum's battlefield effect triggers at the same time as Rek'Sai's legend ability, which resolves first?

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Accepted Answer

Without seeing the exact text of Rek'Sai's legend ability or Candlelit Sanctum's battlefield effect, the general rules are: you must pay a card's printed costs (Energy + Power + any non‑standard additional costs) when you play it unless the effect explicitly says you may play it without paying some or all costs or replaces that payment. If Rek'Sai's legend ability simply lets you play a unit, you still must pay that unit's costs. If both triggers (Rek'Sai's legend ability and Candlelit Sanctum's battlefield effect) trigger simultaneously, the controller(s) of those triggered abilities order them onto the chain per the simultaneous-trigger ordering rules and they then resolve top‑to‑bottom from the chain.

You must pay the unit's costs (Energy, Power, and any nonstandard additional costs) when playing it via Rek'Sai's legend ability unless that ability's text explicitly says you don't have to or replaces the payment. When Rek'Sai's legend ability and Candlelit Sanctum's battlefield effect trigger at the same time, the player(s) who control the triggered abilities order them onto the chain (if both are controlled by one player that player orders them) [383.3.d] [383.3.d.1]. The items on the chain then finalize/resolve in LIFO order.

Determine whether Rek'Sai's legend ability actually instructs you to play a unit and whether its text modifies or replaces the normal payment of costs. If it explicitly says you may play without paying costs or contains replacement language, follow that text instead [357] [131]. If the ability requires you to play the unit normally, when that triggered ability is finalized on the chain you must pay the unit's costs: the combined Energy cost and Power cost and any nonstandard costs listed for that card [357.1] [357.2]. You may use Add Reaction activations to add Energy or Power during the Pay Costs step to help pay those costs [357.1.a] [429.3]. If the triggered ability that plays the unit contains a cost within its instructions (i.e., a cost that appears where costs belong), that cost is a base cost of the triggered ability and must be paid to finalize that triggered ability to the chain [383.3.b.1]. If Rek'Sai's legend ability and Candlelit Sanctum's battlefield effect both trigger simultaneously, the controller(s) of those triggered abilities order them onto the chain: a single player controlling multiple triggers orders them [383.3.d], and if multiple players control triggers the Turn Player starts and proceeding in turn order each player orders their own triggered abilities [383.3.d.1]. Once the triggered abilities are placed on the chain in the chosen order, they finalize and then resolve in LIFO order. Costs that must be paid to finalize a triggered ability are paid during that ability's finalization [383.3.b.1] [357].

If Rek'Sai's legend ability has explicit text that says "play that unit without paying its costs" (or any other phrase that replaces payment), you do not pay the costs—follow the card text. If the ability is worded as a replacement or a delayed replacement (e.g., Accelerate‑style language), follow that replacement; replacements that change payment are still considered paid if replaced by another event in the payment step per 357.2.a. If one of the simultaneous triggers is optional (begins with "you may" in the place that controls whether it is placed on the chain), the controller may choose not to place that triggered ability on the chain, which affects which items end up on the chain [383.3].

Core principle about costs: playing a card requires paying its printed costs (Energy + Power) and any nonstandard additional costs unless the card or effect explicitly says otherwise [357] [131]. That means if Rek'Sai's legend ability simply lets you "play" a unit, you still must pay that unit's Energy and Power cost and any additional costs as part of the normal play process [357.1] [357.2]. While paying those costs, you can use Add Reaction activations to add Energy/Power to your rune pool to help pay them [357.1.a] [429.3].

Triggered abilities that include a cost inside their instructions (i.e., a cost written where costs belong) treat that cost as the base cost of the triggered ability and that cost must be paid to finalize the triggered ability to the chain [383.3.b.1]. So if Rek'Sai's triggered legend ability itself contains additional costs (for example, "Play the top card. As an additional cost to do so, do X"), those costs must be paid during finalization in order to put that triggered ability on the chain [383.3.b.1] [357].

Simultaneous triggers: when Rek'Sai's legend ability and Candlelit Sanctum's battlefield effect trigger at the same time, the rules for simultaneous triggered abilities determine ordering. If a single player controls both triggered abilities, that player chooses the order in which to place them on the chain [383.3.d]. If multiple players control the triggered abilities, then ordering is done starting with the Turn Player and proceeding in Turn Order, with each player ordering their own triggered abilities as they place them on the chain [383.3.d.1]. After the abilities are placed on the chain in that chosen order, they finalize and resolve in LIFO order.

If you provide the exact text of Rek'Sai's legend ability and Candlelit Sanctum's battlefield effect, I can give a precise ruling about whether the unit's costs are waived or replaced and exactly how the two triggered abilities should be ordered and resolved.