The Lissandra Passive
I genuinely enjoy playing Lissandra. I'm happy to get her randomly in ARAM matches, especially. Her passive needs some work. Scarra talks about the gimmicky nature of her passive and Riot has been testing some things this season on the PBE servers. Those tests were all reverted, so I thought I'd offer a suggestion.
"True Ice is a phenomenon that exists only in the coldest depths of the Freljord. A magical matter so cold it can never melt, master smiths have managed to craft this strange substance into powerful weapons and armor."
Lissandra's Passive, "Corrupting Frost" Lissandra's abilities use "True Ice" and corrupt enemy champions damaged by her spells. Corrupting an enemy champion creates an AoE slow around the damaged enemy which grows with corruption stacks. Subsequent spells damaging the same target, stack corruption. When the third corrupting stack is activated, the AoE slow drops from the enemy champion and remains on the field for a short time. Additionally, after applying five stacks of corruption, the enemy champion will be rooted in ice. If the enemy champion moves, the ice around them shatters in a 360 burst, applying corruption to all enemy champions hit by the burst of ice shards. While Lissandra is within her True Ice AoE slow field, she gains bonus defensive stats and Spell Vamp.