The enhanced booster pack format typically offers higher pull rates than standard expansion packs
While a deck like Eldrazi Tron, for example, still uses Leyline of the Void to knock out graveyard decks in the sideboarded games, having access to something that Karn can find in Game 1 gives you the ability to deal with the graveyard in any stage of the match
You could also occasionally lean on Kaldring, the Rimestaff for some recursion, though this is secondary at best, and not usually the reason you're running Jorn
Urborg There is a cycle of legendary lands in Legends , all of which enter the battlefield untapped and can tap for mana of any color, and they also all come with an activated ability
2 = Print separate cards with rarity symbols and no errors, distributed in Packs