The problem is that Kron is faster than all monsters which attack him, so there will be misses.
Torhilo the Frozen: 20% miss chance
Crustacean King: 20% miss chance
Pirate Captain: 10% miss chance

So on average it's not 7 damage per round but 0.8 * 4 + 0.8 * 1 + 0.9 * 2 = 5.8 per round.
Another problem is that Torhilo the Frozen level 1 gets 3 damage (5 -> 3 because of Void) per round but it's healed only 2 HP per round. So Torhilo the Frozen has to be level 2.
If you are lucky this combo can win, but unfortunately, Kron will win most of the time.

Combo that always wins:

• Xander Foxwood
• Unicorn Mustang (level 3) - melee attack: 4, speed: 4, HP: 11
• Wood Nymph (level 1) - magic attack 1
• Child of the Forest (level 3) - ranged attack: 2

So it's 7 damage per round, Kron heals only 6
Unicorn mustang gets 3 damage per round (5 -> 3 because of Void), Wood Nymph heals 3 HP per round
There are 0 misses so this combo wins 100% of the time.