Among the best options for this are Felidar Sovereign with lifegain, Palinchron for infinite mana with Deadeye Navigator, or any of the dozens of combos you can make with Intruder Alarm
The clean play is: Have both faces represented (a double-sided token/proxy token is perfect), and physically flip/swap it when it changes
The kicker (not the mechanic) is that if you Saddle Caustic Bronco your opponent is the one who loses the life instead
If you somehow control a face-down token, you may exile it to activate Primordial Mist's last ability, but you won't be able to cast that token
The last point I want to make on white is that there are quite a lot of four-drops, and unless youre drafting one that serves a very specific purpose, I would consider costing four a point against drafting a card highly
Consequently, the card prices are higher, especially those from the Big Score epilogue set