I started adding all my Legendaries and when I lose a round, I remove the cards in my deck that are in the void and hand that contribute to me losing the game.
Ideally, I'll get the most optimized deck from a local minima.
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.
good luck with that