Necron Deathmark

Flash carries this body, and without it a 5/3 with three toughness would be a liability: too fragile to hold the ground it's built to defend, dying to almost anything on the crackback if you deploy it on your own turn. Held up at instant speed, it changes character completely. You leave mana open, an opponent commits a threat or swings, and you drop it at end of turn to erase a creature and skim three cards off the top of someone's library. The destroy clause is real removal stapled to a flashable body, exactly the kind of tempo swing black rarely gets at instant speed without spending a dedicated card for it; the mill reads as flavor tax more than function, a small rider on the more important half. The toughness is where the design gives back what flash grants: three points is low enough that the 5/3 is meant to trade or sit back rather than brawl, so the enters-the-battlefield value has to justify the slot instead of the combat stats. That trigger is why reanimation and blink shells covet it, since the destroy-and-mill fires every time the creature reenters, turning a flat body into a repeatable removal engine. The Synaptic Disintegrator label is set dressing; the mechanic underneath is a removal-on-a-stick creature that wants to arrive at the least convenient possible moment for the opponent.