It also makes it so that each opponent loses X life and you gain X life, where X is the number of Auras you control at the beginning of your end step
Due to already having the green mana to make the Elf means tapping for just colourless is about as good as you can get and should mean the card outperforms not just other mana elves but also things like Birds of Paradise because of the fixing
Usually its Karn or Ugin in that space
One of the most famous is energy, a mechanic that debuted with Kaladesh and swiftly overwhelmed Standard, which led to a slew of bans at the time
I also count 19 additional Lifegain cards that either gain life or care about gaining life, and 6 additional Token cards that either create or care about tokens
This appears in every Commander deck as removal, but has a secret(ish) secondary mode that can grant you 10,000 life