Nothing: its unlikely, but having one or two certainly isnt
White Cards Knight-Errant of Eos Archangel Elspeth Boon-Bringer Valkyrie Norn's Inquisitor Elesh Norn / The Argent Etchings Alabaster Host Sanctifier Seal From Existence Elspeth's Smite Guardian of Ghirapur Monastery Mentor Invasion of Dominaria / Serra Faithkeeper Zhalfirin Lancer Blue Cards Invasion of Segovia / Caetus, Sea Tyrant of Segovia Chrome Host Seedshark Negate Transcendent Message Faerie Mastermind Moment of Truth Jin-Gitaxias / The Great Synthesis (Untranslated) Six-cost Uncommon Instant (Untranslated) Six-cost Rare Instant Black Cards Breach the Multiverse Phyrexian Gargantua Render Inert Deadly Derision Hoarding Broodlord Grafted Butcher Mirrodin Avenged Invasion of Fiora / Marchesa, Resolute Monarch Traumatic Revelation Archpriest of Shadows Merciless Repurposing Red Cards Chandra, Home's Beacon Scrappy Bruiser Stoke the Flames Voldaren Thrillseeker Invasion of Tarkir / Defiant Thundermaw Into the Fire Fearless Skald Ramosian Greatsword Bloodfeather Phoenix Furnace Gremlin City on Fire Beamtown Beatstick Green Cards Tribute to the World Tree Doomskar Warrior Storm the Seedcore Streetwise Negotiator Ravenous Sailback Invasion of Ikoria / Zilortha, Apex of Ikoria Kami of Whispered Hopes Invasion of Ixalan / Unknown 4/3 Creature Invasion of Zendikar / Awakened Skyclave Wrenn and Realmbreaker Multicolored Cards Heliod, the Radiant Dawn / Heliod, the Warped Eclipse Drana and Linvala Thalia and the Gitrog Monster Yargle and Multani Ghalta and Mavren Omanth, Locus of All Botanical Brawler Halo Forager Etali, the Primal Conquerer / Etali, the Primal Sickness Polukranos Reborn / Polukranos, Engine of Ruin Glissa, Herald of Predation Borborygmos and Fblthp Quintorius, Loremaster Invasion of New Phyrexia / Teferi Akosa of Zhalfir Invasion of Tolvada / The Broken Sky Zurgo and Ojutai Rankle and Torbran Baral and Kari Zev Joyful Stormsculptor Invasion of Moag / Bloomwielder Dryads Hidetsugu and Kairi Invasion of Azgol / Ashen Reaper Errant ant Giada Sculpted Perfection Inga and Esika Invasion of Ergamon / Truga Cliffcharger Kogla and Yidaro Artifact / Colorless Cards Invasion of Ravnica / Guildpact Paragon Sword of Once and Future Realbreaker, the Invasion Tree Lands Wind-Scarred Crag Bloodfell Caves Tranquil Cove Thornwood Falls Swiftwater Cliffs Scoured Barrens Rugged Highlands Jungle Hollow Dismal Backwater Blossoming Sands
Also, you can play a card called Kodamas Reach that does the same thing, which is always valuable in a Commander deck
Malcolm, Alluring Scoundrel Getting to cast free spells with Malcolm, Alluring Scoundrel is appealing
Sure, take three, I guess
