Cap'n Kobold
Hero
OK. And you're burning spells to avoid being hit and go places. What do you achieve when you have got where you want to go?This is a build for going places. Most creatures will find it really hard to stop an unhittable character that can also teleport (misty step, blink, dimension door, teleport, etherealness, PLANE SHIFT).
So they ignore your little dagger pokes until the rest of your party is dead and they can focus on you properly.You can also annoy big strong dudes by poking them with your dagger while they can't lay a hand on you.
Or they just do something that doesn't involve AC, like the opposed Str(Athletics) check for shoving you around or knocking you prone.