This would be a brand new unit, and far from being a hero.
For this to make any sense, game continuity wise, this would either have to be some how accessible at TH1 or an option at TH7, where Dark Elixir can grant you the immortality to take part in all those attacks.
Then, you have to make the user interface for it. Given what you are asking for, it would be safe to assume this avatar unit would have 'favorite target: whatever he whats!' and can pick what to attack. That'll be fun to balance.
Also, you have to figure out abilities, which would have to be set for everyone, or be something selectable and easy for everyone to switch back and forth from. Are you a melee fighting Chief? A ranged fighting Chief? A magical Blaster Chief? A flying unit Chief (likely on a dragon. Like hell inside a bomb filled balloon). An order giving Chief? A troop buff giving Chief? So yeah, deails, what are they?
As much as it would be neat to add in, this would be a major undertaking to do, and will drastically alter the basic way Clash of Clans will be played, forever. This maybe too big of a change, since this would have to be something that the game is built around right from the start.
Not saying it is a bad idea, I like it, but the gameplay business model just seems to say "No".

This could be in CoC 2, but for this game, I highly doubt anything close to what you are wanting will be added, sorry.