Several of these ideas are from https://forums.505go.com/discussion/48958
Planeswalker select screen - it should be much faster to pick a new planeswalker. It currently takes me a full swipe from one side of the screen to the other, and often several seconds per planeswalker.
Converge - show which colors have been paid for the card.
Awaken - prompt before casting all cards with awaken if the cost has been met
Any token generating spell or support that generates tokens when it enters - prompt before casting