So too are other lands that just happen to hit the graveyard a modest amount like Shifting Woodland, Urza's Saga, and creature lands like Raging Ravine
Storm Cauldron returns lands to your hand when you tap them, so you can actually make as much mana as you are willing to pay life
Its not glamorous, but Abrade will simply be the most-played Standard card from Hour of Devastation, even though its in direct competition with Harnessed Lightning, arguably the best removal spell in Standard, at the same mana cost
Valkyrie Harbinger's ability looks at how much life you've gained in the turn, even if it wasn't on the battlefield when you gained life
And with this last one, we get to the end of the list
Some Trainer cards in the set also had an important impact in tournaments, by improving draw and resource management