point n click nuke+cc and retarded laning
uhh
that's not why she's OP? Lissandra doesn't do ridiculously well in a lane without jungler presence.
Lissandra is more OP based on how she controls how the flow of battle goes. Her engage option doubles as a disengage, and her damage + CC ult doubles as a self-save tool. She is OP on the same level of Lee Sin - once proficient in the champion, she maintains control over what happens in a teamfight or what happens in a duel.
Her damage isn't that high considering that unless she hits you with her claw itself, her ability ratios and base damage are mediocre for a burst mage (3 spells for below-average base damage and average combined AP ratio).
Her laning is also not "retarded"...her lane is only good if her jungler actively ganks her lane and have Lissandra's follow up with her ease of engage and CC options. By herself, it's not something deserving of note; unless you also bring in the Top-lane-dominated-by-ranged issue that is prevalent because Riot has no balance perspective on melee-bruiser vs. Ranged mage/bruiser, TBH.
I have laned Talon against Liss and successfully got her to recall twice and teleport into lane once, all the while remaining above half health because her Qs are very much expectable, and the cast frame is actually long enough for someone to dodge the skillshot after they see the start of the animaton. Someone who has ability to gap-close and ranged farming/harassing capability can lane against Lissandra just fine.