This is ok if you just toss it into a deck, and completely breaks the game in half if you build around it. In addition to preventing damage that your hero would take, it also prevents consequential damage to your Champion allies, so you get a free extra use out of each of them. If there's a non-Champion player at the table, use one of your invincible Champion allies to block for them.

The really gross case is a four player game where everyone has a Champion hero, a pile of Champion allies, and a copy of Go For Champions in their deck. There will be large portions of the game where nobody can be hurt AND you can still make a ton of forward progress on the villain. Who cares about Universal Weapon or Fanaticism if nobody can take damage?