I think it would be more visually engaging and more efficient if there were obvious cues when a spell or skill fails to resolve properly on the target.

Using Slow for an example, let's say that I cast it on a marmot. The spell fails, and the only way I can know this is by watching the battle log or noticing that tiny icon hasn't appeared next to the critter's health bar.

This isn't usually a problem if I'm playing solo, but with a party member up front attacking the target and inflicting status effects of his/her own it can get confusing.

It would work well if when a spell was cast on an enemy and resisted there were either different animations to show that the effect did not take (a distortion effect, the animation not fully executing, etc.), or even a text popping up "Resisted!" on the target.