Clash of Clans: Upgrading heroes while in war

Solution 1:

When heroes are upgrading:

  • They cannot defend the village from regular attacks

  • They will defend your village in war at the level they were when preparation phase finished

  • They cannot be used to attack on war nor on regular attacks.

If your heroes upgrade gets finished on war attack phase

  • You CAN use them to attack in war but they will continue defending with the level they were when preparation phase finished

It looks confusing, but actually is pretty simple. You'll get used to it.