It depends a lot. Usually I want to use it to resolve my survival. If the battlefield is full, a PW is a pretty good target, if your hand is slow sometimes you can't beat an arcanist and the recalls are never bad targets for it either. With Leo to help getting an advantage and some flusterstorms (I play 2), summer veil and misstep you can change gears according to the situation.
The best results I get are with blue-heavy lists, as I can get slow them down and protect myself instead of having ouphe and FoV. I mean, I still have some of them in the deck, they just don't make it to games 2 and 3.