[Rework concept] Diana
Passive - A circle of moonlight surrounds Diana at all times. Enemies within the moonlight are nearsighted. Radius: 450 units.
Q - Diana receives movement speed towards enemy champions hit by her Q.
W - Diana's moonlight grants a short duration shield to her and her allies. The shield has a high base value that is distributed evenly between all friendly champions. Every point of damage absorbed empowers Diana's next Q.
E - Heavily slow enemies within Diana's moonlight and puts them into a trance after 2 seconds from activation if they are within the moonlight. Diana's next attack on a tranced target will deal heavy damage. Trance: renders the target unable to control their character for up to 2 seconds until they receive damage similar to being asleep.
R - Diana can cast her moonlight to a chosen nearby location for X seconds (revealing the area). If an enemy champion is tranced, Diana can cast this ability to teleport to the target and reap the enemy dealing heavy damage based on the target's missing health while becoming untargetable during the cast animation.
Trying to hit that "beautiful executioner" vibe opposed to the "murderous executioner" which is portrayed by Kayn. Similarities can be seen in their ults.
I saw that her theme could be intertwined better with her gameplay and tried to create something a bit more unique with the whole moon theme.
Her gameplay style would probably shift from a bruiser/assassin to a skirmisher/assassin hybrid.