Honey, oh honeeeey....
Just don't play her. She's trash. Rito was going to make changes to her last season and somehow ended up forgetting about it completely.
She's in a really odd position. She's suppose to be somewhat tanky (but she's not), and please don't get me started on her abilities (her abilities may as well just heal the enemy champion). Overall, she's been irrelevant for the longest time. For a champion who has such a cool lore, a persona of a wicked ice witch, she really just hits like a snowflake (and is squishy as one too!). GJ Riot.
Also, that passive of hers, that's some irrelevant flop assery. Riot literally took lissandra's passive and put it on a rune. Like, seriously, girl?
Why not just make her passive be something like, "Every time Lissandra uses an ability, half her health is drained. Also, she takes double damage from enemy champions. Yes GAWD." Ugh, buff the ice witch or rework her somehow. Make her relevant again. Jesus christ.
And also, would Riot be nice enough to release a nice skin for her? Like, yeah, I get it, her particles are hard to work with. But seriously, her last skin was two years ago and it looks like garbage. You guys barely put any effort into her particles (specifically the ice molecules etc.,). Program Lissandra looks ugly, dull, and half-assed. You guys just wanted to release a skin for her and were lazy to put in the effort to make it look decent.
Honestly, all the fan art that's been released for Lissandra, why not take some of that into consideration and make a nice skin for her?
tldr; REWORK or BUFF her damage. Toplane soraka is more of a threat than her. Ice Witch my ass, more like "Lissandra: The melting popsicle stick."