Rhystic Study is an exception, but that card has maintained a $700 price for a while now
There was once a deck that played Puresteel Paladin and another similar card (to be seen later on this list) and a bunch of zero-mana equipments like [c]Paradise Mantle[/c] and [c]Kite Shield[/c]
Protect your already established board from mass removal using cards like Selfless Spirit and Teferi's Protection
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Cards like Fiery Emancipation, Thousand-Year Storm, and Niv-Mizzet, Parun can drop away with a touch of burn, and Izzet stalwarts like Goblin Electromancer, other spellslinger cards like Archmage Emeritus, and then a suite of blue countermagic can amp up the attack
My gut says to not have any, but I could be wrong