mtg secret lair commander deck preview Weekly Update (Aug 06): First Cards From Upcoming Secret

Once sufficiently buffed, Esper Sentinel wont only be a force to be reckoned with

As the term suggests, the rarities each signify different percentages for how easy or difficult it will be to find one of these types in the booster packs of cards for the game

It enables you to play cards, typically instant and sorceries, for a huge discount, so long as its the first card you drew this turn

The first is Background, which will appear on specific Legendary Enchantment cards that can be attached to their chosen commander

While its a cost four character and uninkable, its ability is also quite strong at enabling you to get characters into your hand, and it also benefits from powerful questing once you mange to get enough characters in play