The Standard version of Dredge looked to use discard outlets like Llanowar Mentor, Merfolk Looter, and Magus of the Bazaar to get dredgers like Golgari Grave-Troll, Stinkweed Imp, and Life from the Loam into the graveyard
Manifesting a card puts it onto the battlefield as a 2/2 creature, and you can turn it face-up by paying its mana cost
Its first mode is basically just Call the Coppercoats, which is solid enough, but if your Commander is on the field, then you also get to kill one of your opponents creatures for free
Giving your opponents free cards isnt the best, but the Snakes will no doubt make up for it
While you cant use it to come out ahead on a sweeper in the same way that you would with other white protection spells, there will definitely be circumstances where you dont mind saving the many in order to save the few