When it comes to talking about seasonal mode, I never see any talk about this seasonal mode. For those uninitiated, power shift mode is where a unit's power is set to it's provisional cost. On hearing this you are already thinking about draw your gold's the game, but it surprisingly well balanced.
This is hands down my favourite seasonal mode because of some interesting and fun plausible decks.
Back in the day, Lippy decks used to be king of this mode, but I am not so sure if they are now. However, here are a few ideas I had that you guys can try out.
ST harmony. Easily my fav deck for this mode. All the harmony cards get an automatic buff. Poison is a great tall punish and add in geralt for another and you are set.
NG Spotters. Easy to get a good reveal when the floor is 9. (4 reveal + 5 base power). NG also has a lot of control options making it threatening
MO deathwish. Ruehin buff might make it a little weaker and the nerf to OW leader doesn't help. But it is still worth playing for some massive points. Remember to carry good amount of tall punishes else you will loose to a control deck.