Cultivate You might be shocked to hear this, but Cultivate is the fourth most popular Commander card, according to EDHREC
Joke(?) aside, this could be part of a fragile combo-esque RG Prowess deck but is otherwise unexciting
TheChirurgeon: It's really cool that Bahamut is colorless, as one key thing about Mega Flare is that it often deals non-elemental damage, making it distinct to fire/ice/lightning magic in terms of how it's handled with regard to resistances
10 Scion of Draco It's 12 Mana, What's The Problem
For the third Mystical Archive card in the Collector Booster, it will always be a traditional foil uncommon Mystical Archive card
I do appreciate how broad it is, but hopefully you can just play Sephiroth's Intervention or Fate of the Sun-Cryst instead