Abilities

Spooky Pop 
Super: Swing mace, deal 4 DMG, push back and 1s Stun nearby enemies
Max 4 damage, 2s stun

Spooky Pop 
Super: Swing mace, deal 4 DMG, push back and 1s Stun nearby enemies
Max 4 damage, 2s stun
+1 damage
Lvl 1+1s stun
Lvl 6+1 damage
Lvl 11

I am back! 
Revive: Return to battle with 10 HP plus 4 HP per Soul (Boast: +1 Soul
Max 8 HP and 2 Energy per soul

I am back! 
Revive: Return to battle with 10 HP plus 4 HP per Soul (Boast: +1 Soul
Max 8 HP and 2 Energy per soul
+2 Energy per soul
Lvl 2+2 HP per soul
Lvl 7+2 HP per soul
Lvl 12

How dare you! 
+2 DMG to Isolated enemies
Max 2 DMG, 2 Energy Absorb

How dare you! 
+2 DMG to Isolated enemies
Max 2 DMG, 2 Energy Absorb
+1 Energy Absorb
Lvl 3+1 Energy Absorb
Lvl 8+2 DMG
Lvl 13
Stats
HP 15
DPS 2
Attack 4
Hit Speed 0.5
Energy Cost 10
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 enemies. 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.