The Bite-Sized series of articles is meant to take the most powerful cards in Dominion and give a short explanation of what makes them powerful.
Champion is an extremely powerful effect, and makes a lot of very powerful decks possible. Infinite actions is, of course, a huge asset when there are lots of terminals you want to play, especially ones that draw cards. This effect alone is almost always worth opening Page for, and it’s almost always worth focusing the first ten or so turns of the game on getting Champion in play as quickly as possible. Naturally, the strongest synergies here are trashing or anything else that helps your play your Travellers sooner.
Getting complete immunity from attacks is a great effect as well. However, most of the time you should still invest in attacking your opponent just to slow their Champion down. Of special note is Warrior, which can trash your opponent’s Warrior, slowing their Champion down enough to be game-decisive most times this happens.
Champion is not the complete focus of every game it appears in, but Page offers support for money-focused decks as well with Treasure Hunter and Hero, which can make Page still worth going for in these situations.