Untargetable Champions/Abilities

It's something I really like. But often you have new or lower ranked players complaining about it being OP, broken, or unfair.

I disagree with that but I feel if there were a visual cue as to whether the champion is able to go untargetable it would relieve the frustration of new players by a great deal. This should have almost no effect (or more likely none at all) with more experienced or higher ranked players, since they know about and expect these abilities, and often try and bait them out.

An animation kind of like a single foxfire slowly orbiting the champ (altho less intense as it can't damage enemies.) Or an additional bar under the mana bar, think annie.

Just an idea that might help relieve frustration from new players, and give them an easier understanding of the enemies they are facing. The only issue I would see with it would be clutter around the champion. This also could give you some unique opportunities to play with this mechanic in a more fair way.

TL;DR A visual cue for Untargetability may relieve stress and frustration for new or inexperienced players, and most likely have 0 effect on game balance.