This website (which is not live at the time of publication) is also going to provide some info when its ready
There are several options available, like Arbor Elf or Elvish Mystic, but Llanowar Elves is the blueprint from which all others were based
So, if you have them both in play, Sephiroth can sacrifice Aerith for his fourth trigger, transforming, and then reap the benefits of all the +1/+1 tokens Aerith had built up from his attacking
You play Baru and return it to your hand with the trigger from Nature on the stack
Although the Autumn release isn't set to hit stores until November, the final mainline Sword and Shield expansion has had many of its cards already revealed in the Japanese sets Incandescent Arcana and Paradigm Trigger
I think all colours should have some ways to interact with peoples plans that are not limited to things in play (or graveyards)