The ShiftstonedEternal Power Calculator is a deck-building tool that visualizes your odds of drawing enough Influence and Power based specifically on the cards found in your deck.
The main problem I've had with Feln Control is that it feels more like a midrange deck, in that you're often out of cards and in top deck mode. She provides so much advantage in these situations. I've been playing Feln pretty much exclusively since I started playing, and she actually makes the deck feel powerful enough in the late game to actually call it a control deck now.
In the deck that I have on my profile, I like to keep hands with some early interaction, a Suffocate or an Extract, and either a Wisdom of the Elders or little Vara. Scout for Power very aggressively, cause even with 30+ sources it's very easy to get stuck on three or four, and you really want to get to 5 and 6 so you can start playing more than one card per turn.
For sure. I definitely prefer little Vara over the Feast-Callers. I also can't imagine running this deck with only 25 Power. Even with 3 Seek's and the Vara's Favor I can easily see this deck struggling to hit Power number 4-6. I plan on trying out Hailstorm tomorrow after I pick up the campaign.