To ensure your deck is Modern legal, it must contain only cards that have been printed in the following sets (any version of that card is fine):
- Ravnica Allegiance
- Guilds of Ravnica
- Core 2019
- Dominaria
- Rivals of Ixalan
- Ixalan
- Hour of Devastation
- Amonkhet
- Aether Revolt
- Kaladesh
- Eldritch Moon
- Shadows over Innistrad
- Oath of the Gatewatch
- Battle for Zendikar
- Magic Origins
- Dragons of Tarkir
- Fate Reforged
- Khans of Tarkir
- Magic 2015
- Journey into Nyx
- Born of the Gods
- Theros
- Magic 2014
- Dragon's Maze
- Gatecrash
- Return to Ravnica
- Magic 2013
- Avacyn Restored
- Dark Ascension
- Innistrad
- Magic 2012
- New Phyrexia
- Mirrodin Besieged
- Scars of Mirrodin
- Magic 2011
- Rise of the Eldrazi
- Worldwake
- Zendikar
- Magic 2010
- Alara Reborn
- Conflux
- Shards of Alara
- Eventide
- Shadowmoor
- Morningtide
- Lorwyn
- Tenth Edition
- Future Sight
- Planar Chaos
- Time Spiral
- Coldsnap
- Dissension
- Guildpact
- Ravnica: City of Guilds
- Ninth Edition
- Saviors of Kamigawa
- Eighth Edition
- Betrayers of Kamigawa
- Champions of Kamigawa
- Fifth Dawn
- Darksteel
- Mirrodin
The following cards are not permitted in Constructed - Modern decks:
- Ancient Den
- Birthing Pod
- Blazing Shoal
- Chrome Mox
- Cloudpost
- Dark Depths
- Deathrite Shaman
- Dig Through Time
- Dread Return
- Eye of Ugin
- Gitaxian Probe
- Glimpse of Nature
- Golgari Grave-Troll
- Great Furnace
- Green Sun's Zenith
- Hypergenesis
- Krark-Clan Ironworks
- Mental Misstep
- Ponder
- Preordain
- Punishing Fire
- Rite of Flame
- Seat of the Synod
- Second Sunrise
- Seething Song
- Sensei's Divining Top
- Skullclamp
- Splinter Twin
- Stoneforge Mystic
- Summer Bloom
- Treasure Cruise
- Tree of Tales
- Umezawa's Jitte
- Vault of Whispers