If Blue Ezreal is attacked and the attacker passes priority, can you use his action to move him to base before his 'when I defend' damage resolves?

Ruling: No, you cannot use the action until after Ezreal's 'when I defend' trigger is resolved. The triggered ability goes onto the initial chain and will resolve before either player would have open focus to play an action.

Sequence:

• When Ezreal defends, his 'when I defend' trigger goes on the initial chain
• This triggered ability resolves first
• Only after that chain resolves can you use the action to move him to base
• While there is an ability on the chain (triggered or otherwise), you can only play reaction speed abilities

Nuances:

• The 'when I attack/defend' triggers always form the first chain, and once that chain resolves, it goes to the normal chain where you could then use actions