Navajo

The reason it's so fiendish in Navajo is because they're not one or two little irregularities. There are lots of them. Things move into different slots, but only with some conjugations and not others. Some disappear and only leave a tone change behind. So it can get quite complex. And you have plain vowels, nasalized vowels, high or low tone, and they all combine. That leads to crazy diacritants. Yes, lots of anonymous system type. I mean, it's pretty standard.