The deck is a White, Blue, and Green (or, Bant) deck that revolves around creatures that enter with +1/+1 counters, that synergise with Tidus, Yuna's Guardian's abilities
Gettin Mama Odie, Mystical Maven out there early - which should be doable thanks to the cheap cost of the card - alongside a handful of songs, will very quickly put you into a position wherein you can play a lot more cards per turn or a much more expensive, and more powerful, card a lot earlier than your opponent
Modern Horizons 3 contains the 5 basic lands (Plains, Island, Swamp, Mountain, and Forest) with variant treatments, plus an uncommon Snow-Covered Wastes (included as one of the 101 uncommons) with its variant treatments
We decided early on that they would care about frogs mechanically
Cards that do well competitively that are also incredibly rare tend to deliver a lot of value