Ian didn't wait to see if his surprise attack worked and was quickly trying to fumble with the keyring and find the right one. When he got it and was about to unlock the cell was when the mage's lightning hit him. What realy saved Ian was the lack of metal on him, currently the only bits he had were his daggers and the keyring, both of which acted as sort of lightning rods and redirected most of the poorly aimed attack. The keyring directed some of it to the lock since it was close and that seemed to serve the same purpose of unlocking it, but the rest hit him, and while not nearly enough to kill him, it stunned him and ultimately planted him on his ass.

Still shaking his head and recovering from the fall he saw Tahra come out of the cell, say something about the guards and coming with her, and immediately sprint off and jump out a window. Not exactly how he planned this, but then again...he didn't really plan any of this. Not wanting to wait for the mage to get back up or for guard to reach him he got up and followed Tahra with a murmur of "ugh, princesses" jumping out the same window into the river.