Greninja and Zoroark are important inclusions in Unbroken Bonds, with more gorgeous art to deliver
Because of the way Kroxa and Kunoros' ability resolves, you can sacrifice it in response to the reanimation clause, sacrificing it to the Altar, to mill six cards and then exile five of them to return Kroxa and Kunoros to play, triggering its ability again in an infinite loop
Mana Tithe, as the most powerful among them, became an instant cult classic
Doubling the mana produced by your islands enables some incredible turns, especially with effects like Turnabout and Time Spiral
Helper cards are especially useful at Limited events, prereleases, or casual tables where someone asks, "Wait, what does this emblem/token/dungeon do again?" for the sixth time during a game
It's still my favorite common piece of equipment and haste is really important here as we only copy attacking stuff