Some, like Huntmaster of the Fells started becoming popular in the Jund builds that emerged after the banning of Treasure Cruise and Birthing Pod in February, but as there were not a single major Modern event until last weekends StarCityGames Invitational, his price stayed low for months and only spiked this week when the wolf is out of the bag
In addition in comses with a 10/10 body, Flying and protection from white and from black, so with Haste it can be a finisher
A good start includes 35-39 lands and a handful of rocks, though certain decks (particularly artifact-focused ones like Breeches, the Blastmaker or Slobad, Iron Goblin) will play more
Each has their advantages, but the strongest is probably We Dont Talk About Bruno
If a creature card is exiled this way, you gain 2 life