Because normally it doesnt get card draw as good as Chandra, Pyromaster and Read the Bones, it normally doesnt get such a good sweeper (Anger of the Gods), and it normally doesnt get so much good discard
At the end of your opponents turn, youd use Foundry to sacrifice Meek to summon a 1/1 Thopter token and gain 1 life
The third commander in the set was Kestia, the Cultivator, a commander who cares about enchantment creatures
Tyranid Prime has Evolve and gives every creature you control Evolve as well, making it pair nicely with Simic Ascendancy
Aim for that player with the lower mana cost cards until you get enough elves or faeries, then your card advantage can steer you to victory
Both of these material types offer high quality protection for your collection and are worth heavy consideration when shopping around