[Suggestion] Lissandra passive

I have two ideas that i have been thinking of that might be pretty cool.

If we want to keep something about her mana problems

• Free spelln every 18 seconds ----> If you land a spell on an enemy champion you receive 20 missing mana restored. (10 second cooldow?)

Or if we want something completely new

• Each consecutive spell used on a champion (4 second window to hit next spell) the slow on champion is increased by 20%. It will freezes(cc) the enemy for 2 seconds upon reaching 100% slow

The only problem is ultimate gives 75% slow. So I would make it so ultimate disables the passive or something.