Can a player respond to an Action with another Action, and can an Action be played after a Reaction is used in the chain?

Ruling: Actions cannot be used in response to another Action. Once an Action starts a chain and that chain fully resolves (including any Reactions played to it), then the opponent gains Focus and can play an Action.

Sequence:

• Player plays an Action (like Disintegrate), which starts a chain
• Opponent can respond with Reactions, but not Actions
• Once the chain fully resolves with any Reactions that were played
• The opponent gains Focus and can then play an Action