With the newer upgrade, when we cast spells such as silence, we receive a note if it's possible to even silence the mob, when we fail. This is a great addition, in my opinion.
But it'll be nice to see the puppet realize it's not possible. Yesterday I was killing CC and the entire time he refused to stop casting silence, which the fish is immune to. Either make the puppet some what intelligent and have it stop casting spells that are not possible to land, or give us an attachment that prevents it. Maybe cast once after that it learns it the target is immune and stops trying.