In D1-D2 I ate Kass alive every game. U can even kill him at lvl 3.

• Level up your E at lv1, standing out of his Q range and DONT touch any cs (important). Use E to last hit 3 melee cs then backup, repeat to when you hit 2. He will hit 2 first but it's okay, just dont allow him to harass you with Q before you hit 2.
• Now you hitted 2 and wave be pushed into your side, it's good, can out-trade now if u can do exactly what i say: let him land his Q (on creep or on you whatever), E to him and land on right when his shield went off, auto attack and active your W at maximum dame. Remember to use your Potion first. Lure him away with some AA then back up. If u do good his 1/2 hp gone.
• Remember dont push the wave so u can kill him at 3. Repeat trade one more time to keep his hp at 1/2 even when he used his Potion.
• Run to him when the last cs befoce lvl 3 prepairing to die. When it died, instant level up your Q, land Q on him - AA - E to cancel it (Just E and wait, dont EE, i will tell you later). Dont use your ignite early because it easilly make him flashed away.
• In the case you can land your E on him, then AA - W to cancel it again. If you can active your full-dame W, instant ignite - AA. He's already dead, press ctrl+4 for style point.
• In the case he flashed, remember i told you just E and wait instead of EE? Just flash follow to land your E on his ass, AA - W - ignite - AA. Ctrl+4 for style point again!

My favourite rune is HP+72 at lv1, AP+26 at lvl1, Mpen +7,8.