Gizel, The Forgotten Watcher
Gizel, The Forgotten Watcher Passive - Fractal Touch - Whenever Gizel casts an ability it creates a frozen area on the map that last for 10 seconds, interacting with all of her abilities. Enemy champions that walk over the frozen path cannot stand in one place, they slide slowly in the direction they were heading before they stopped, but they do stop after a second or two.
Q - Cold Kiss - Using her ice magic, Gizel blows a gust of wind dealing magic damage to all enemies in a wide (aoe size is the same as cassio ult, I would imagine) cone slowing them down if they are walking towards Gizel. If an enemy is standing on her frozen path while she casts this ability, they are snared for a short period. Using Cold Kiss on a pillar or spike shatteres them in a target direction, but it is better if it is cast on a line of spikes for more aoe. Deals heavy magic damage. If an enemy is hit she regains some of her missing mana (only applies when used with W). This ability does not deal a lot of damage on it's own.
W - Watchers Seal - Gizel creates a small pillar of ice on the ground dealing magic damage. If the pillar is cast on a frozen path, it creates a short line of ice spikes, blocking enemies from walking past it. The spikes face in the direction opposite of Gizel, while also adapting to the direction facing enemies and last for a few seconds. Enemies standing directly in front of the spikes take damage over time according to their maximum health for as long as they stay in that area. Semi-Low cooldown. Instant cast. Spikes cannot be destroyed or absorbed by yasuo windwall, as they are True ice.
E - Curse of the Forgotten - Gizel's magic is unstable. When this ability is activated she creates a frozen path around her in a small area, spreading and following her where ever she goes for as long as it is active (can te toggeled on/off like Karthus E. Her other basic abilities enjoy signifficantly lower cooldowns while this is active. Long cooldown on active. This ability has a passive that gives Gizel increased movement speed when walking on frozen path. Movement speed bonus scales with ability power. Ice spreads faster in the river.
R - Crystal Heart - Gizel marks one enemy champion with true ice. After a short delay they take magic damage, while other enemy champions or minions are slowed for a few seconds. If cast on an enemy that's standing on her frozen path, they take true damage scaling with their maximum health. This ability negates shields and reduces healing ONLY WHEN empowered by her passive.
Visually, I'm not really sure how she would look, I imagined her as a snow queen or something, but I'm not really sure about that since there is already Lissandra and all. She would be wearing a dress made out of ice, her hair would be short and white (maybe?) while her skin would be pale blue (or however the watchers looks like visually). She would also have a lot od ice particles and such on her abilities and maybe a snow flake following her around.
I only made her up about a week ago, so I haven't got any ideas for her voice lines or any special interactions :-D