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
The point of the card code is that it labels not any one particular card but a particular slot
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
Price $35.80 Another classic Doctor Who artifact, the Tardis provides you with free planeswalking and cascade abilities so long as you're playing with a Time Lord, and with 29 to choose from, you certainly won't be starved for choice
On cards that don't get a security stamp (usually commons and uncommons), the acorn will be a printed stamp where the security stamp would have been
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