Putting a card in a double-sleeve or perfect fit upside down, and then in a regular sleeve correctly gives you maximum protection from any spilled liquids or from dirt that might get in your sleeve.
I would likely play four Threnody Singer in the sideboard although it seems better than Brineborn Cutthroat against aggressive decks, I want a two-drop that lets me play an aggressive role against slower decks in game one
I'm not sure if it has a place in Standard, but in Commander I could see some major combo potential
Mycosynth Lattice turns everything into an artifact, and crucially, that includes all your opponents lands
Other versions in the Secret Lair drop use regular capitalisation, and are cheaper as a result
Getting one Treasure per rotation of the table, unless your opponent really wants to draw cards, isnt worth a four-mana investment