Here's what your lookin' for: Trelane's phylactery, Trelane's orb, an' Trelane's ember agate.
All three should be in chests within the tower an' you shouldn't have a problem opening the chests on your own; you just have to be careful of the ogres.
The tower's defenses won't take care of 'em on their own; you'll need to have your weapons at the ready. Those ogres find out you're there and stealing from 'em, an' they'll be sure to put the hurt on you.
Be careful, an' good luck.
Malin couldn't've asked a worthier person to come here an' aid us, <name>. You've done a grand job!
He'll be pleased to see what an overwhelming success our mission's been.