Once you take down the tier 1 tower in your lane, proceed to the jungle with morbid mask and only leave when you have your blink. With blink you can now engage easily. Ulti, Mask of Madness, bkb, blink in, stun, hit, rampage, ggwp. Late game you might want to buy a moonshard to consume. You may also want to swap out your MoM with a Satanic. Remember Sven is a nuker, so find the best opportunity (Most number of heroes clustered together or their carries) to blink into the fight and just rape everyone's butt.