Deploying cards and initiating abilities is a core part of the game. There are many interrupts and reactions to this process, most notably cost reduction interrupts, and it may not be obvious exactly where these interrupts/reactions kick in during a deployment/initiation, nor some of the implications. This tutorial attempts to bring added clarity to this area for the advanced player.
The process for deploying cards and initiating abilities is outlined in the RRG Initiating Abilities/Deploying Cards section (pp 8-9), and states:
“When a player wishes to deploy or play a card, or initiate a triggered ability, he first declares his intent. The following steps are then observed, in order:
1. Check play restrictions: can the card be deployed or played, or the ability initiated, at this time?
2. Determine the cost (or costs, if multiple costs are required) to deploy/play the card or initiate the ability.
3. Apply any modifiers to the cost(s).
4. Pay the cost(s).
5. Choose target(s), if applicable.
6. The card is deployed/played, or the ability resolves.”
The first thing to note is that steps 1 are 2 are pre-process checks. It’s only if you satisfactorily pass these first 2 checks that the deployment/ability initiation process is permitted to actually initiate. This means that the deployment/ability initiation process (hereafter called “the process”) in reality only consists of steps 3 through 6.
In other words, the rulebook is first ensuring that the game state allows the process to be initiated (steps 1-2), and then outlines the steps within that process once it’s initiated (steps 3-6).
After you’ve declared your intention to deploy or play a card, or initiate a triggered ability, the first “check” step is performed.
Step 1: Check Play Restrictions - Play restrictions are constants and are therefore continually checked intra-game. This step is a reminder of that fact. If you can’t satisfy its play restrictions, you can’t initiate a deployment/ability. Also, if the ability being initiated uses the word “target”, then an eligible target must exist, per the RRG Target section:
“If there is no valid target for a targeting effect, the ability cannot be initiated.”
This is another form of play restriction.
Because these are continuous state of play considerations, and not a framework event, there are no interrupts/reactions to this step.
Step 2: Determine Costs – In this step, you need to prove that you can afford to pay all relevant resource costs and ability costs of the card.
RRG 1.2 (pg 23) states:
“A player is not permitted to deploy or play a card he cannot afford; however an interrupt ability to deploying/playing a card may be used to reduce an unaffordable card’s cost to an amount that the player can afford to play.”
This gives you permission to initiate the process if you don’t have the requisite resources to pay for it, as long as you can prove to your opponent that you can make the card “affordable” through the use of abilities (if he requests such). This may require showing cards from your hand to do so. Once proven, this step is passed, and you’re permitted to initiate the process (if still desired).
Note that an event action may have both a resource cost and 1 or more ability costs (per RRG Costs: The Word “To” section, pg 5). For these, you must demonstrate that you’ll be able to pay all costs simultaneously, without relying on any single cost being paid first (eg not relying on a benefit from an interrupt to one, which then helps pay for another).
In this step, no card interactions are taken into account (eg if an ability cost requires you to exhaust a unit, as long as you have a ready unit that can exhaust, then the check is satisfied. If it would die due to a Dire Mutation before it actually exhausts, that doesn't matter, as card interactions are not checked).
One common question is whether a card must be ready for its ability to be initiated. These two steps do not specify that that's required, therefore no, its not a baseline requirement. An exception is if the ability has an ability cost that requires it to exhaust - then the card must be ready to be able to "afford" to pay that cost.
(Eg: When you deploy a unit, When you trigger an ability, When your opponent triggers an ability).
An interrupt window now opens that allows interrupts to both the commencement of the process as a whole and to Step 3: Apply Modifiers, the first step in the process. This interrupt window is where cost reducer interrupts (for example) would be triggered.
If a cost reducer interrupt is cancelled, or the cost is increased by an ability, then you must continue the process if you can still afford the card using the resources you have and the modifiers you declared in Step 2. If it would take additional modifiers that were not a part of the initial determination of the card’s affordability in Step 2, you have the option to use these modifiers to prove that the card is still affordable but you’re not required to do so —you may abort the process. If you continue, your opponent can ask you to demonstrate that the card/ability is still “affordable” - if you cannot do so you must abort the process.
(Aside: The reason for “proving” is to stop a player from performing cost reducer interrupts for the purpose of gaining secondary benefits without actually completing the process. Example: When I deploy a daemon unit, I can sacrifice a cultist token to reduce its deployment cost by 1. If I have an ability that allows me to gain a card each time I sacrifice, this stops a player starting or continuing a deployment that they can’t complete just to sacrifice units to get those extra card draws.)
Once the interrupt window closes (by the usual two successive passes), the process continues.
Step 3: Apply Modifiers - Cost modifiers are now applied to determine the “resource cost” to be paid in the next step.
Cost modifier interrupts always trigger on the overall process rather than to this specific step, so in practice there are no interrupts/reactions to this specific step (eg no “when you modify a cost, …”).
Step 4: Pay Cost - For deployments, pay the “resource cost”. For abilities, you may have a “resource cost” if the ability is on an event card being played, and/or you may have 1 or more “ability costs” (ie the text which precedes the word “to” within the ability). In this situation, you must pay all costs simultaneously, without relying on any being done first in order to generate benefit (eg from interrupts to it) that helps pay for another.
In practice, there are no interrupts/reactions to this specific step (eg no “when you pay a cost, …”), but there may be interrupts/reactions to the initiation/resolution of an ability cost (eg an ability cost stating “Exhaust a unit to …” may lead to interrupts/reactions to a unit being exhausted).
If any portion of the cost payments fails (eg due to such an interrupt), then the ability initiation process aborts. You don't get a second shot at paying the cost. All other costs must still be paid however, because they're paid simultaneously.
Step 5: Choose Target – If the ability you’re initiating contains the word “target”, you now choose an eligible target, where eligibility is defined by the ability. (Note: This step is only relevant when initiating abilities, not deployments.) While Step 1 required that an eligible target existed, it’s only in this step that you’re required to choose your target, and there’s no requirement that the target you choose was one of the eligible targets available in Step 1. As long as it’s eligible now, that’s all that matters. If a change in the game state between step 1 and step 5 results in a situation where there is now no eligible target, the aspect of the ability that needs to choose a target will fail to resolve in step 6.
In practice, there may be interrupts/reactions that trigger to the choosing of a target.
Step 6: Resolve - At this point, the deployment actually occurs, or the event card is played and/or the ability’s effect resolves.
In practice, there usually aren’t interrupts to this step as they’re triggered in the opening interrupt window.
Reaction Window – this is to both Step 6 and the resolution endpoint combined:
(Eg: After a unit deploys, After a unit enters play, After you use an ability, After you resolve/play an event card)
When an effect is cancelled, it’s important to know that steps 3 through 5 are still processed, even if the effect was cancelled in the opening interrupt window. This is because the game is very careful to only ever cancel effects, not abilities (an effect being a subset of an ability), which means that it’s only ever Step 6, the resolution of the effect, that is cancelled - not the other steps. It also means that all costs are always paid regardless of cancellation.
The RRG Initiating Abilities/Deploying Cards section (pg 9) states:
“If any of the above steps would make the triggering condition of an interrupt ability true, that ability may be initiated when that triggering condition becomes true. If any of the above steps would make the triggering condition of a reaction ability true, that ability may be initiated just after the triggering condition becomes true.”
This can lead to confusion because it implies this is a common practice, and easy to construe that a given interrupt/reaction occurs within the process rather than pre/post. In practice, as per the above rundown, it’s quite rare.
After discussion with the FFG design team, this is my updated understanding of the process. I hope it’s helpful in providing clarity around exactly how things work, but if you have any questions, please ask.