I guess the stuns could be split into two trees too. Silences, and roots.
Also things like stuns can break on damage, or they should have a short immunity after the first cast. I think 30 seconds is too much, more like 5-10 sec seems more reasonable.
This also assumes that a character is going to eventually have more than 4 active abilities to choose from, when they should, since we have so little quantity of actual demigods.