This progresses you through the Account Mastery levels and the levels for the newest set.
Naturally as you play, you’ll earn experience. Wild cards can be redeemed for any card of their rarity and are crucial to building decks.
Some packs replace a card with a wild card of the same rarity, but with every pack you open you earn credit towards additional ones. Opening packs and achieving particular mastery levels reward wild cards tied to Magic’s different rarities: common, uncommon, rare, and mythic.