Can I use reactions to respond to when I attack or defend triggers?

Yes, you can use reactions to respond to "When I attack" and "When I defend" triggers.

According to RiftJudge FAQ #6106 and RiftJudge FAQ #8093, these combat triggers create a chain, and because reactions can be played in response to any trigger on the chain (or during a closed state), they are eligible targets for reaction-speed effects.

How the Timing Works

When a combat showdown begins, the following sequence occurs according to the Showdown Timing Flowchart and Rule 459.2.d:

1. Trigger Placement:
   • The attacker places all their "When I attack" triggers on the chain.
   • Any other non-defender players (in turn order) place their triggers.
   • The defender places all their "When I defend" triggers on the chain.
2. Locking Choices: You must choose all required targets for these triggers before any player is permitted to play a reaction (see RiftJudge FAQ #10000 and Rule 402.1). You cannot wait to see if an opponent reacts before deciding who your ability targets.
3. Reaction Window: Once all triggers are on the chain and all choices are made, the state becomes Closed. Players may then alternate playing reactions to the chain.
4. Resolution: The chain resolves in LIFO (Last-In, First-Out) order. This means the last items added (typically the "When I defend" triggers) will resolve first.

Important Reminders:

• No Actions: You cannot play [ACTION] cards while there are items on the chain (including combat triggers). Only [REACTION] cards can be played at this time (see RiftJudge FAQ #2281).
• Trigger Conditions: As noted in Rule 383.4.e and Rule 383.4.f, these triggers only trigger the first time a unit gains the Attacker or Defender designation during that specific combat.
• Optional Triggers: If a trigger says "you may," the controller chooses whether to place it on the chain at all. If they choose not to, it cannot be reacted to because it never enters the chain.