Auras are the best way to boost Sigardas power since a Selesnya commander has access to all the best enchantress cards, including Sythis, Harvest's Hand and other enchantresses to draw cards and spells with umbra armor like Snake Umbra to protect Sigarda from those board wipes
Exploration plus Crucible of Worlds plus a landfall trigger that fills the graveyard doesnt feel like something that should have been printed on an individual card
Meanwhile, Adewale Breaker of Chains can search up a pirate or vehicle (or an assassin if you really want) when he enters play
Getting the two best creatures from your graveyard is much better than drawing two random cards when built around properly, something the Golgari decks can do with ease
Given that Bloomburrow feels like a more accessible set than, say, Outlaws of Thunder Junction, it stands to reason that itll be getting its own dedicated Starter Kit, which will help players learn how to play with two pre-constructed, full 60 card MTG decks (and useful accessories too!)
Mutational Advantage being a thematic protection spell is incredible because you get so much more out of this than you would a measly Heroic Intervention