Can you respond to non-reaction activated abilities (like Vi Destructive, Sett Brawler, Udyr Wildman) with removal spells to kill the unit before the ability resolves?

Ruling: You can only respond to activated abilities with reaction-speed cards. Most removal spells are actions and cannot be used in response to abilities.

Nuances:

• Shakedown and Gust are examples of reaction-speed removal that can be used to kill units in response to their abilities
• Action-speed cards cannot be used in response to effects on the pile/chain