Talk:Kassadin/@comment-7409578-20130420231327/@comment-4659858-20130421223100

It's an early game item you get when you are heavily behind and can't really fight so you can keep up in items and DPS (you use R to flee but your combo comes back sooner) in teamfights. Allows you to push better, farm under your tower better and backdoor better.

Not really worth it if you aren't behind though, because straight AP/mana/HP will be much more effective. If you ARE behind use the CDR and AS to depush hardcore and then try to gank/countergank. If you ever land a kill push the tower as hard as you can with your increased AS buff.