Can Sett Brawler and Udyr, Wild Man spend their buffs as a reaction, or only during an open non-showdown state?

Ruling: They can only spend their buffs on your turn, while there's no chain and no showdown. These abilities are base speed, not reactions.

Nuances:

• Anything that doesn't explicitly say "Action" or "Reaction" is base speed
• Base speed abilities can only be used during open game states on your turn