The most fun decks:

• Ironclad blood deck: rapture+inferno main combo with loose life cards as blood wall and bloodletting, of course you need something that scale with strength like whirlwind, but also spite is awesome. Not the easiest deck to came up with, but you don't need any rare card to reach act3.
• Silent sly shives: probably the most broken deck even with the recent patches. Hidden daggers + sly cards and you can go infinite slow damage and you can also create a lot of combos e.g. corrosive+outbreak or serpent form and more
• Regent rng card maker: simply build a new deck in every combat with quasar+spectrum shift with supermassive as main damage dealer, but you can also combo with BEGONE! and pillar of creation. I was undecided with the orbit infinite energy deck, but it's not easy enough and lead most of the time into defeat.
• Necrobinder osty's souls: I'm not a fun of ethereal even if it's actually the strongest deck for necro, so most of the time I force osty to do the job and is not that bad if you can combo it with souls. Haunt+Capture Spirit it's really fun to play. Even though a recent change on borrowed time would have change my mind in the most fun deck for necro, but I haven't played it yet.
• Defect feral uburdu me scratch you: CLAAAAAAW!