Two weeks since the launch of "Hearthstone: Knights of the Frozen Throne" expansion, the second wing of the solo adventure opens the Upper Reaches of the Icecrown Citadel. Here, three bosses are waiting for the player, who must defeat them in order to unlock new paths to the Lich King.

Blood-Queen Lana'thel, Professor Putricide, and Sindragosa are the three opponents that the player must beat. All three focus on shifting hero powers, so those battling them must have a deck that takes those shifts into account. Lead Designer Dave Kosak released some notes that will help players beat these bosses.

Lana'thel uses a typical Warlock deck except at the beginning of the match. She turns your hero into a vampire with the new hero power "Vampiric Bite," which costs zero mana and gives a non-vampire minion +2/+2 and the "vampire" type. The catch is that you have to use this hero power on every turn, even on Lana'thel's minions, if you run out of targets of your own. The challenge for the players will be to keep enough minions on the board so they will always have a target to bite.

Facing the second boss, Professor Putricide, will produce some crazy battles because of his hero power "Mad Science." First, he will set all Secrets to cost zero mana, then he will make all weapons cost one. Later on in the match, he will set the cost of everything to five.

A deck with lots of weapons and Secrets will be the key in order to take advantage of the cost reduction. Having a good card draw will also help, but due to the nature of the opponent's power players will have to get creative in beating this mad scientist.

Lastly, Sindragosa's hero power, "Frost Breath" will permanently freeze all enemy minions. Players will have to find the correct timing to sacrifice their own minions while keeping enough slots to fight off the boss. A minion-heavy deck will not be advisable against Sindragosa, and unfortunately, she also punishes players who have lots of spells.

As Dot Esports notes, a Control Paladin deck will be very helpful against Sindragosa, and the addition of Alexstraza may be the key in defeating her.