Corellon's grace allows you to move when others take action.

Encounter ✦     Channel Divinity, Divine
Immediate Interrupt      Personal

Trigger: A creature within 10 squares of you spends an action point to take an extra action.

Effect: You take a move action.

Special: You can use only one channel divinity power per encounter.

Published in Player's Handbook, page(s) 194, Class Compendium.