At the moment it’s kind of this weird thing where you can mouse over an enemy and have them technically be “targeted”, but this only really matters for direct target spells such as Lunge. For ranged spells that fire projectiles like, say, Fireball, it doesn’t seem to actually do anything. It still fires where your cursor is, which means that the projectiles can actually just skim past enemies unless you are aiming directly at the middle of their feet.
I don’t know if this is intended or not but it makes ranged spells feel very awkward. Not just on large enemies, but on regular sized enemies too. And no it’s not dodge either, I can do this very consistently. It would be nice if it was closer to how Lightning Blast functions, but with a less extreme lock-on; just point the cast at the targeted enemy.