You can add one loyalty counter to create a 1/1 white and black Spirit creature token with Flying, and remove two loyalty to exile a creature you control and then also exile up to one target creature from every other player
12 Grolnok, The Omnivore It eats everything
Well only discuss cards that have the text gain life. Lifegain is an effect primarily seen on white cards, with black cards and green cards coming in a close second and third
With cards like Yorion, Sky Nomad, you can blink Out of Time, get your creatures ETB effects, then re-phase the battlefield and get a fresh set of counters
At the current box price, thats ~648,000 spent on average to pull one meaning the cards 448,000 market price actually represents a discount versus pulling it yourself