We've seen enough of this ability to know that it's at the very least playable, but the ones in the past require a bit of context to understand why they're playable
At 1 mana, you cant get much better value for a hard counter, and stopping that specific noncreature spell from resolving is often way more important than the two extra mana theyll have on the following turn
Come on, how can this not be the best
Make sure to check back soon for more precon content here on EDHREC, because Duskmourn will be here before you know it
As a player becomes the monarch, the current monarch (if any) ceases being the monarch
The idea is to resolve this (as early as turn 1 with a Dark Ritual) and stack your library with a sequence of game-winning cards, usually a couple of cantrips and a Thassa's Oracle