Each Maze of Muertos booster pack contains 7 cards:
• 1 Foil card per pack
• 6 Rare cards per pack

source: product page

In addition to the cards in the product page announcement, we can also spot the following cards on the cover:

[Alternate Art] Uria, Lord of Searing Flames
Drawbread
Primalight
Treasure Panther
Elemental HERO Thunder Giant – Voltic Thunder
Drill Armed Dragon
Light Water Dragon
Masked HERO Atomic
Over Future Fusion
Hero’s Rule 1: Five Freedoms
Masked HERO Furnace
Mikanko Divine Dance – Futahashira no Uzu no Miko
Gargardo the Necroforger Fiend
Junk Mail
Masked HERO Dusk Crow
Soul of Gaia the Fierce Knight
Einroid
Soul Union
Nurikabe
Uzuhime the Manifested Mikanko
Magnet Warrior Omega+
Festiballoon
Ritual of the Matador
Dragonic Warrior
Archfiend Matador
Secret Stash Slipshod Squirrel
Dogmatika Chaplain
Bazoo the Soul Eater Beast
Veiss Shark
Shadow Trouble
Sanaki the Mikanko Devotee
Shateki
Eucalyptus Mole
Chaos Distill
Burgundy the Magic Elf
Dark Magic Amulet
Arequus the Shining Mars Saint
Starship Adjust Plane