What it does
Manifest dread tells you to look at the top two cards of your library, then put one of them onto the battlefield face-down as a 2/2 creature (it's "manifested"), and put the other into your graveyard. So you're filtering: you keep one as a hidden creature, you bin the other.
The key nuance: a manifested permanent can be turned face up at any time you have priority by paying its mana cost—but only if it's a creature card. Lands, instants, and sorceries stay stuck as 2/2s. Also, manifest dread digs through two cards but only one ever becomes the creature; the choice happens face-up to you, so you decide which to hide and which to discard.
In Commander, it's solid card selection plus board presence, and it enables graveyard synergies by intentionally binning fuel. The hidden information also creates bluffs—opponents don't know if your 2/2 is a vanilla land or a flip waiting to ambush.













