Boom Grenade + DIO - latest step to be played

[prisma dirge]

Context:

• Hero: Dash I/O
• Attacked with an attack action
• Opponent has declared no blocks
• Priority is sitting with me in reaction step
• Boom Grenade on the top of the deck

Question:

• When is the latest I can play this Boom Grenade off the top so that it triggers?
• Must it be played in Reaction Step? I’m guessing there’s no window in Damage Step?

Follow up Question:

• How does the stack work in the Damage Step? Do On Hit effects (like Boom Grenade) go on the stack? Does the Attack Action Damage itself go on the stack or is it just dealt immediately?

[deft grotto]

The latest you can play Grenade and still have it trigger is the Reaction Step. After both players pass in Reaction Step, the game moves to the Damage Step, damage is calculated and dealt, any hit triggers go onto the stack, and players receive priority.