Obviously the more restrictive a cards mana cost the higher its opportunity cost and vice versa, which is a major reason why Smugglers Copter was so oppressive
If gaming pulls some evil out of you, and you like to show cards to your opponent and then make them discard those cards, then you can put these to good use: Razorkin Needlehead, Smothering Tithe, and Fate Unraveler
Seat of the Synod is the king of the colored lands, because blue is the color that works best with artifacts, and Vault of Whispers is second because of Disciple of the Vault, but all of them have joined the fun at one point or another
Generally, the smaller mana cards with more stringent deck requirements are better in 1v1 formats, while cards with less requirements are better for Commander
Sanctum of Shattered Heights
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