IMPORTANT: Fitting Guide Listed Below
The reality is that the card can be great once you're already online with your strategy, but is probably less efficient at setting that strategy up
The first Landfall triggers manifest dread (look at the two top cards of your library, turn one into a face down 2/2 creature and send the other to the graveyard)
Similarly, if The Soul Stone is already harnessed and becomes a copy of something else, it stays harnessed, though it's very likely that won't be relevant until that copy effect ends
When it enters the battlefield, it exiles target spell with a converted mana cost of four or less, and when Spell Queller leaves the battlefield the owner of the exiled card can cast that card without paying the mana cost
We have a wonderful card that holds up the Coin Flip archetype, the Chosen Digit that points the flock of crappy jank into the direction of playable mediocrity