Abilities

Passive 
Super: Swings his mace in a circle, pushing away opponents to the tune of 12 damage, and stunning them for 2s

Promotion 1 
Isolated opponents suffer an additional 4 damage and 2 energy steal

Promotion 2 
On Revive, gain 150% HP Steal and Rage

Promotion 3 
Boast: summons a skeleton warrior.
Super gains +8 damage.
Stats







Skeleton Warrior (Promotion 1)
HP 12
DPS 2
Attack 2
Hit Speed 1
Classes

Undead
Skeleton King Counters
Skeleton King is a pretty adaptive Hero and can destroy teams that are not prepared. The main tactic you don't want Skeleton King to accomplish is attacking Isolated opponents. Try to position your Troops on the sides of the boards where they won't get pushed too far back from his Super.
Tanks and high-health Minis are great up front to keep him from stealing Souls for a better revive. Then, ranged units can also help peck away at his health from a safe distance.