Here is how I would buff lux:

The current pbe buffs only make her more of a low elo stomper but still unreliable in high elo. Instead, I would buff her utility to make her more of a utility mage by increasing shield strength or something else. Option A: Shield strength: 50/65/80/95/110+0.2ap -> 50/75/100/125/150+0.25ap Option B: Shielding an ally now gives then 10/12/14/16/18% movespeed for 2 seconds Option C: If the shield hits an enemy, it reduces their mr by 10/15/20/25/30 for 2 seconds