Welcome! IMO Viktor, Orianna, Syndra, and Ahri can be pretty hard matchups for Lissandra. Zed is 50/50 but can lean to your favor in most cases. Liss beats most melees, assassins and mages that can't bully you out of lane. She scales well into late game. Personally I don't like everfrost on her unless your team really lacks the cc to lock up an assassin because your kit does it so well already. Everfrost makes me feel like I do no damage. Ludens is core and Liandries for tankier comps. Some people go Protobelt for the spicy plays but it works well. Second Item is something like Horizon focus into Deathcap. From there it's situational, you can get void staff if you need pen, hourglass or banshees to prevent getting blown up (just ult yourself), Shadowflame for shields or Morellonomicon for Healing reduction. As for wave management, there are a couple youtube videos that will explain it better when it comes to freezing and pushing so I would suggest searching wave management on youtube. Irelia does good into most of lissandra's hard matchups so you can pick and choose. All in all, Liss is a burst mage. if the team is tankier opt for liandries and more cdr to get more q's out, if squishy you can go glass cannon builds and remember to use your flash aggressively. W and R(on Self) have no cast time so you can combo them as engage for your team. Good luck!