Im enjoying this Seasonal mode more than i anticipated. My favourite is still Season of the Draconid (and im still hoping for a permanent Blitz mode) but i like this one.
My favourite aspect - you dont need necessarily to build specific decks for this mode. Yes, there are a few tricks that can help, and there's definitely already a meta faction for this mode, but the truth is you can use any deck and if you play well you can win. Sometimes even a bad hand is enough, because your opponent will suffer with it too.
My new advice for this mode: round 1 tends to be full, 10 turns, so R2 and R3 are usually only 3 cards/turns.
If you choose a leader ability with just 1 powerful charge, you have much better chances to win these small rounds, but on the other hand, leaders like Crach or Meve are helpful on long R1s.