Core problems are:
a) Emperor reducing cards/spells to 0 mana.
b) Frothing Berserker gaining attack-damage from enemy minions.
Problem a) is a huge thing, because you can fit in more/unlimited combo pieces within a round. See the Soulfire nerf. Same thing. 0 mana cards are OP as hell in Hearthstone.
Solution to a) is simple: don't let Empereror reduce cards to less than (1).
Problem b) makes the game non-interactive and you are punished for extending into the board. Similar problem with Unleash the Hounds, just here it is much more devastating for you.
Solution to b) is simple as well: make Frothing Berserker only gain damage from your own minions.