mtg warhammer 40k secret lair card list Deck box listing may hint at Secret Lair x Warhammer 40,000:

They enable surprise plays, counter enemy spells, and provide combat tricks that keep opponents guessing

If You Had to Just Pick One Set Blossoming Calm | Illustration by Michael C

As Jihad enters the battlefield, choose a color and an opponent

The resulting artifact creature will be able to attack on your turn if it's been under your control continuously since the turn began

Rhystic Study is by far the game's best card of its kind, effectively taxing each opponent 1 mana each time they cast a spell Spells are constantly cast in Commander, so Rhystic Study's controller will draw lots of extra cards if the opponents aren't paying 1 extra mana

Of course also perfect for the collectors among us