They wont play around a one-casting cost removal spell because there are so few Dark Betrayals going around which will (under the right circumstances) let you waltz them into your trap
You need to beat them at the minigame honestly
like Mirrodin and Darksteel (and Scars of Mirrodin, Mirrodin Besieged, and especially New Phyrexia), Fifth Dawn doesnt exactly truck in cuteness
The ability isnt bad, and its definitely very lore-friendly considering Galadriels internal conflict regarding the Fellowship, but I think it can be a little unfocused
Apart from one- and two-mana card draw / discard spells, with the addition of Prized Amalgam, it's completely possible for Dredge to win games without ever casting anything, just like in Legacy and Vintage
Living Death Living Death (no, not Living End) is a 5-mana sorcery that basically swaps the creatures in play with the creatures in graveyards