Morgana new mechanic "Anti-Aid"
Anti-Aid is a new mechanic that prevent a target from accepting any aid from their allies example: heals, shield, lantern etc. The reason why i think morgana should get this ability is because it fit that theme of her being a fallen angel that dam all soul.
You can add this effect to her current W and make it so while they are standing in the area they will be under the effect of Anti-Aid.
Another suggestion i have for morgana is buff her passive alittle make it scale up during the game from 20/25/30% would be a nice.