If Warwick moves into the battlefield before damaging units with an action spell, does Warwick still kill them, or should damage be applied before moving Warwick in order for him to trigger?

Ruling: Warwick triggers immediately when moving into combat, but only units already damaged when the trigger resolves will die. Action spells cannot be played in response to Warwick's trigger because a chain already exists and only Reaction speed spells can be used.

Sequence:

• Warwick moves into combat and his "When I attack" ability triggers, forming the initial chain
• Only Reaction speed spells can be played in response to this trigger
• When Warwick's trigger resolves, he kills any units that are damaged at that moment
• After the chain empties, Action spells can be played, but Warwick only checks for damaged units once when his trigger resolves

Nuances:

• If you damage units with a Reaction speed spell (like Flurry of Blades) in response to Warwick's trigger, those units will be damaged when Warwick's trigger resolves and will die
• When multiple "When I attack" triggers occur simultaneously (like Anivia and Warwick), you can choose the order to place them on the chain