You could make a pretty standard +1/+1 counter deck, or go the opposite route with -1/-1 counters
A Killer Among Us Acid-Spewer Dragon Acidic Slime Acidic Slime Aether Poisoner Aetherblade Agent Age of Ultron Agent of the Fates Agent of the Shadow Thieves Agent's Toolkit Ahriman Akroma, Vision of Ixidor Alchemist's Gift Alela, Artful Provocateur Alesha's Legacy All-Out Assault Alpharael, Dreaming Acolyte Ambush Viper Anhelo, the Painter Animus of Predation Ankle Biter Ankle Shanker Aphelia, Viper Whisperer Aragorn, Company Leader Archetype of Finality Archpriest of Shadows Argivian Avenger Arisen Gorgon Armed Assailant Arno Dorian Arnyn, Deathbloom Botanist Arvad the Cursed Ashnod the Uncaring Ashnod, Flesh Mechanist Aspect of Gorgon Assassin Initiate Astarion, the Decadent Atraxa's Skitterfang Atraxa, Grand Unifier Atraxa, Grand Unifier Atraxa, Praetors' Voice Aurora of Emrakul Aveline de Grandpr Aven Heartstabber Avenger of the Fallen Axebane Ferox Ayli, Eternal Pilgrim Baleful Eidolon Baleful Strix Bane-Marked Leonin Barrowgoyf Basilisk Collar Battle-Rage Blessing Battlefly Swarm Bebop, Skull & Crossbones Bilious Skulldweller Binding the Old Gods Bitterblade Warrior Bitterheart Witch Black Waltz No
Playmats Playmats are the next most important piece of the puzzle for Magic players
It's fantastic in Legacy because you have a plethora of fetches, but in cube it's much more rare to get a shuffle effect, let alone being able to pair it with Brainstorm
