Champions can be cloned, but when you use its ability, only the non-Cloned Champion will activate its ability, so it is unrecommended.

Can you mirror champions?

Mirror cannot be used on Champion cards. If the player's last played card was a Champion, the Mirror will ignore it and repeat the card played before the Champion.

Is clone a good card clash Royale?

Clone Spell is a 3-Elixir card that copies any of your troops in a radius of 3. These clones have the exact same stats as the original save for the health, which becomes 1. The Clone Spell is a very risky card to play and even riskier to play if you are not fully aware of its potential.