344. During a Showdown , the player with Focus may do one of the following:

344.1. Play a spell that is legally timed.

344.1.a. The spell will start a Chain as normal.

344.2. Activate Abilities of Game Objects that are legally timed. See rule 357. Abilities for more information.

344.3. Pass.

344.3.a. If all Players have passed once in sequence, the Showdown ends.
344.3.a.1. Perform a Cleanup.

344.4. Otherwise, Focus passes to the next Player in Turn Order.