If Warwick moves to a battlefield and starts a showdown, then in response to his 'When I am attacking' trigger the attacker plays Cannon Barrage and the opponent removes Warwick from the battlefield, does Warwick's effect still resolve?

Ruling: If Warwick is removed from the battlefield before his effect resolves, his effect will not work and will resolve to no effect.

Sequence:

• Warwick moves to battlefield and starts showdown
• Warwick's "When I am attacking" trigger goes on the chain
• Attacker plays Cannon Barrage in response
• Opponent removes Warwick from battlefield
• Cannon Barrage resolves, dealing 2 damage to all units at that battlefield
• Warwick's effect resolves but does nothing because he is no longer at the battlefield

Nuances:

• Target legality is checked on resolution
• When legality cannot be determined (such as effects that reference "here" when the unit is no longer there), the effect whiffs
• The effect is not independent of the card