Please tell me how to use Barbarian King effectively?

Use the ability when in the red and take out the cannons!!!

The barbarian king is the most powerful of them all.
It has an ability called the iron fist that can be used starting from level 5 which can be used during attacks.
It produces a rage spell around him that helps in regaining his health, making a group of up to 20 barbarians appear and also affects other barbarians inside the spell making them go faster and stronger as to what the rage spell has its effects.
During raids, he is best to use with the healer and archers as supporting troops.
Barbarians can also be a good supporting troop for your king because it can affect other barbarians near him when he goes in rage.
Use the king’s ability when he had lost a portion of his health and deploy as many barbarians when he uses this ability.
During battles at clan wars, he can be deployed as any other regular troop.
It is most useful in ground attacks with other troops such as the golem, PEKKA and wizards.
It can also help in destroying remaining buildings so that a three star win can be obtained.
However, the barbarian king can easily be killed by a group of archers and barbarians since it only attacks a single target and its attack speed is quite slow.
In using the barbarian king as a defensive troop, put in near the clan castle in the middle of your village.
It will attack enemy troops that comes in proximity but retreats when lured to far from his patrol area unlike the troops inside the clan castle.