You can pay X, one red, and one green, to grant a Wolf or Werewolf you control +x/+0 and trample until the end of the turn
Obelisk of Urd isn't really exciting when it hits only one creature, but +2/+2 is a sizable bonus, and even a few creatures receiving the bonus is enough for it to matter
Only a few hundred copies of the card exist, so theyre coveted by collectors
Parallax Wave Perhaps a bit high on the list considering its a tap-out four-mana card, but in my experience, Parallax Wave elevates any creature-based deck
Graveyard decks have always been a huge part of Magic , ever since the first Animate Dead was used to cheat out the first Lord of the Pit or Shivan Dragon
The good news is that most green decks in most constructed formats play Boseiju, which means if you have been playing other formats you likely have these, or if you want to branch out at some point Boseiju will be useful in other places