Undefeatable

If you care about someone, you'll become friends! If you care about each other, you'll become many times stronger! And your bravery will be unlimited! In this world are many unpleasant things, many sad things, and many that, which you can't handle by yourself. But while you have people you care about, you just can't fall! You just cannot surrender! While you have those people, about which you care, you will stand up again and again! That's why Hero is absolutely undefeatable!

Near-synonyms: impregnable, impenetrable, unassailable, unconquerable

When the Marshal is removed from the game board the General is undefeatable and its value needs to be changed accordingly.