You can have up to 4 copies of each card, and its generally best to go ahead and include the maximum number of copies of each card to increase your chances of drawing the cards you want and to focus your deck on a specific play style or goal
Arena adopted this mechanic for Brawl, allowing players to build decks with two commanders a move that many see as a stepping stone to full multiplayer
64x Card Sleeves
Photos and condition notes are your next checkpoint
Support & Control Spells: Call the Coppercoats, Dire Tactics, Treacherous Terrain, Sylvan Reclamation for removal and reach Ambitions Cost, Painful Truths, Mass Appeal keep the cards flowing
Most other decks have haste creatures, flash creatures, or large numbers of small creatures, and those arent what Tamiyo wants to play against