Your Win Condition
Farm until six. Trade when you have first item.
General Strategy
Max Q>E Focus on dodging qs. She does no damage with her q if you are not poisoned. Don’t trade with her early or try to cheese her with lethal tempo in lane. You can’t stick to her and she has more sustain than you. Go Dshield and second wind for sustain. Try to be unpredictable with your movements so she q’s early. You can cancel autos when last hitting and walk away so she is baited into q’ing when you last hit.
Trading Patterns
Do not trade with Cassiopeia early on. After six you can look for autos on her when her q is down.
Wave Management
You want the wave near your turret so she can't run you down. Try not to push the wave when you are farming with q.
Their Win Condition
She will look to harass you when you try to farm and run you down with her e. She should try to trade ults with you at 6 since her ult is on a lower cooldown than yours.
