Admonition Angel, Avenger of Zendikar, Emeria Angel, and Rampaging Baloths will provide continual upside, especially if you want to play Wheel of Sun and Moon and Zuran Orb to keep cycling all the lands through your deck while gaining bunches of life
Not so bad in a Bloomburrow Draft and other MTG formats where you can run multiples, but Commander limits you a bit
If it tries to put an instant or sorcery card onto the battlefield this way, that card remains in its current zone instead
You can copy a fetch land to ramp out a bunch of lands at once, or copy a game-winning ability to end the game in a wild way
The most coveted among them is the Kairiki Charizarda famous error cardwhich is traded for prices of over 1,500,000 JPY (~US$10,100)