Anyone collecting purely for sentimental reasons should grab this one
Green/White/Blue: Counters - Ramp (+1/+1 Counters, Ramp, Blink) This color combination has one of the weaker identities in 2x2, as evidenced by its signature uncommon: Bant Charm, a generically useful spell that doesn't really play into a theme
These have gone in and out of stock, so you might have to check back later if initial preorders sell out
If youre building a multi-color elemental shell or the popular Dance of the Elements archetype, this is an auto-include that provides the kind of explosive ramp that wins games by turn four
On second thought, why not play them together
Ravenform lets you exile an artifact to make a 1/1 blue Bird, making just one copy with Mystic Reflection, while Starnheim Unleashed lets you make as many 4/4 Angel Warrior tokens as you can pay for with its XX and one white mana cost