ARAM: reduce Shields on others (just like healing)

The change to make healing half as effective when used on others actually did fairly well at "fixing" healers in ARAM. (Though Sona is still excessively powerful there.) However, champions who can shield others are also powerful, for many of the same reasons, and it seems to me that they need a similar change.

Consider the champs that give a HP shield to others: Lux, Karma, Sona, Janna, Lee Sin, Morgana, Orianna - all of those shields are extremely powerful in ARAM, and all of them could stand to be reduced. Meanwhile, the self-shields usually are not really so much of an issue, and are generally okay where they are.

Thoughts?