93/94 Old School: Madrid Rules

Deck Construction Rules

Cards per deck: At least 60 plus a 15 cards sideboard.
Allowed sets: Alpha, Beta, Unlimited, Revised, Arabian Nights, Antiquities, Legends, The Dark, and Fallen Empires.
Reprint rules: Every reprint that is Old Frame, uses the original art and is non-foil is allowed.

Contemporary rules and errata are followed, with a few exceptions:

Chaos Orb: 1, Tap: Choose a nontoken permanent on the battlefield. If Chaos Orb is on the battlefield, flip Chaos Orb onto the battlefield from a height of at least one foot. If Chaos Orb turns over completely at least 360 degrees during the flip, and lands resting on the chosen permanent, destroy that permanent. Then destroy Chaos Orb.
Falling Star: Choose any number of non-overlapping creatures on the battlefield. Flip Falling Star from at least a height of one foot. If Falling Star turns over completely at least 360 degrees during the flip, it deals 3 damage to each chosen creature it lands resting on. Any creatures damaged by Falling Star that are not destroyed become tapped.
Ring of Ma’rûf: 5, Tap, Exile Ring of Ma’rûf: The next time you would draw a card this turn, instead choose a card you own from exile or from your sideboard, or any other card you own that is legal under the banned and restricted list, and put that card into your hand.

Banned: Bronze Tablet, Contract from Below, Darkpact, Demonic Attorney, Jeweled Bird, Library of Alexandria, Mind Twist, Rebirth, Tempest Efreet.
Restricted: Ancestral Recall, Balance, Black Lotus, Braingeyser, Channel, Chaos Orb, Demonic Tutor, Mana Drain, Maze of Ith, Mishra’s Factory, Mishra’s Workshop, Mox Emerald, Mox Jet, Mox Pearl, Mox Ruby, Mox Sapphire, Regrowth, Sol Ring, Strip Mine, Time Walk, Timetwister, Wheel of Fortune.

You can find more information about this format on their website.