Can I activate Voidreaver Kha'Zix legend abilities during Showdown if I have Focus?
No, you cannot activate the legend abilities of Voidreaver during a showdown.
Ruling: Activated abilities that do not have the Action or Reaction keyword can only be activated during your turn when the game state is Open (the chain is empty). Because the legend abilities of Voidreaver lack these speed keywords, they cannot be used during a showdown, regardless of whether you have focus or are attacking or defending.
Reasoning:
- Ability Timing: According to Rule 347 and the standard rules for activated abilities, an ability must have an Action or Reaction keyword to be used during a showdown. Since the abilities on Voidreaver ("Spend 1 XP, [T]..." and "Spend 2 XP, [T]...") lack these keywords, they are not legally timed for the restricted environment of a showdown (Rule 344).
- Showdown State: Even if you possess focus, you are limited to taking Discretionary Actions that are legally timed for the showdown state. Activated abilities without speed keywords do not qualify.
This interpretation is supported by RiftJudge FAQs 9120, 8584, and 9157, which clarify that legend abilities lacking speed keywords cannot be used during a showdown.