I love league right now

with locket + redemption she has next to no ap so there is no reason for sorcs, so the only other options are ninjas, mercs, or cdr. Depending on how the game is going she might need the mobis to get back out on the field and be with her team faster.

It gives her a better map presence. Say Thresh. If he goes those boots, he can go from bot to mid in record speeds without abilities. Granted this is more of a support build, so I am guessing she can use that speed to join team fights, provide shields and ward all the more quicker.