It's for instant positioning and escape. In that particular game it's good against Wisp/Tiny because you can blink relocates on you. It's also good against QW Invokers because you can dodge the Tornados. The Mjollnir was a waste though, I think. But Sniper was a bad pick overall. No matter what items he bought he would need a BKB+a lot of items to take down the Tiny because of Tiny's E.