flask & 3 hp pots -> Roa -> athene (20% cdr and mana regen) -> sorc boots -> morm (20% cdr and mana regen) -> zhonas -> rabadon i'm not hear to win lane, if i do get the upper hand then lucky me, but undoubtly the top laner is going to lose out on a lot of damage just trying to counter me specifically if they start stacking mmr, once i get roa i can just farm very easily and even more so with athene. but it usually results in the lane being frozen until the laning phase is over or me just winning from pushing there turrets back so far.
So what happens when you both recall and they come back with a negatron and 2 longswords vs. your flask and catalyst?
You say you arent trying to win lane, that's fine if you scale super well, but without a void staff you aren't going to outscale someone who builds a spirit visage and merc treads. Especially if your items at the time are RoA, Athene, Morellonomicon as opposed to Athene, Zhonyas, Void.
I'm not trying to knock you down and say lissandra top isn't possible. It may be good for all i know, I've certainly seen my fair share of them. I'm just questioning the build path. I play a lot of top lane and I rarely lose to AP tops when I just get a fast negatron. If I'm winning lane it means I can bully their jungler, take a fast tower, teleport in for dragons, etc. And I don't have to play a lane bully to do that either if my opponent is intentionally gimping their early game with a catalyst.
EX: If I pick rumble and rush an abyssal scepter, you're going to lose to me in lane and get outscaled heavily in teamfights as well.