All these considerations apply to the Nature vs. Haven situation. This is the first thing you shouldn't forget! If you manage to apply Forgetfulness to the elves, what can Nature do in response? In reality, only with the Anti-Magic spell (the selected unit gains immunity to all types of magic for the duration of the battle), which must be cast on the elves before Forgetfulness. And removing charms and exorcism are not Nature's forte!

That's why I love archmages. And that's why I don't hesitate to write about it in every thread! They don't have these problems.