Ah, Grim Patron. You are indeed a horrible plague upon the beauty of Hearthstone. Almost every Hearthstone player has faced this deck, capable of one-turn-kills that are impossible to prevent, at least once in their time playing.
The basic concept of the deck relies on a few core cards from the Warrior class, found across the Expert, Naxxramas, and Blackrock Mountain sets. Warsong Commander is the first card that will be played, a 2/3 minion for 3 mana that gives life minions summoned by its controller charge, or the ability to attack on the turn they are summoned.
Next, the Warrior plays Frothing Berserker and Grim Patron. Frothing Berserker is a 2/4 minion for 3 that gains 1 attack for every time a minion takes damage. In many games of Hearthstone, the opposing player will have several minions with attack values less than 3, allowing the Warrior to attack into those minions and buff their Frothing Berserker while multiplying their Grim Patrons. In addition, the spell Whirlwind, that deals one damage to all minions on the battlefield for the cost of one mana, can be used to further increase the number of Grim Patrons and damage counter on the Frothing Berserker.
Pretty simply put, this is a pretty powerful combo. The biggest problem that arises from the combo’s power is that it is so good as to be able to deal more than 30 damage in a turn without having played any other cards in the turns before. No other deck in the game has the power to win the game with such alarming power while requiring no setup on the battlefield. That creates a problem for Hearthstone both at the casual and professional level.
While Secret Paladins and Totem Shamans may be the more popular decks on ladder in the post-TGT environment, Patron Warrior has not lost its effectiveness. It continues to be an effective but overpowered deck that wins consistently at a high win-rate.
Patron is a problem due to its overpowered abilities making it almost a requirement to either play or counter, with either choice taking up a dedicated deck slot of the three given to tournament players. The last time a deck was comparable to Patron was in the early days of Hearthstone. The Hunter card Starving Buzzard was a 2 cost 2/1 minion, and it would be played in almost every hunter deck because it gave the player a large advantage over their opponent through card draw.
With the release of Naxxramas, Blizzard nerfed the card to its current stats: a 5 mana 3/2, practically killing the use of the card. To rebalance the game, Grim Patron Warrior also needs such a nerf. The best card to target with this nerf would be either Frothing Berserker or Warsong Commander, the two key pieces of the combo pie that hold the entire Patron game plan together. Without them, the deck would be weakened enough to revise its role as well as its structure and back off to allow Hearthstone to become balanced once again.