@bazaarofbaghdad See this is exactly the kind of effect that doesn't interest me? I'm not saying this card would be bad or ineffective, but problems creep up.
If you play a card like this against a Mentor deck and they draw one of their already maindeck Fragmentizes, you're not really in an interesting position. If they have a hand that doesn't happen to have Force of Will in it, this doesn't even really hurt them. Note that as written, that effect doesn't actually stop Mental Misstep because phyrexian mana is paying it's mana cost, but I'll take it as a good faith argument and assume we want some wording of the card that prevents them from paying 2 life but not one mana. In that case Misstep is still a fine card, it's just very slightly worse, to the point where they're probably still ahead, given the fact that you lost a card to do this.
This card absolutely does a number on Sphere effects, no doubt about that - but you're really only doing better than removal if they have a hand with 2 or more Spheres, and if they have a very typical aggro hand this is going to do nothing at all.
Dredge loses their Dread Return and Hollow One which is a neat side effect, though you wouldn't put this in a sideboard just for that.
Oath probably doesn't care at all.
But what does it cost you to run this card? You can't be running anything with alternate casting costs, so if your'e playing a deck that would otherwise have that, you're sacrificing that option to get this. I'm not sure if you want it to affect Delve or not (I don't know how to make the wording different off the top of my head), but if you want that, you're sacrificing your access to Delve cards as well.
I think for most decks running this card makes your position worse in the metagame than it makes your opponent's (I think this is going to be a problem the new Damping Sphere has as well, but the way). Looking at this card I think there is one exception though. As this is basically only good at answering Force of Will, and Sphere, but bad at answering any aggressive hand, it could be a good fit in a deck that is weak against Force of Will and Sphere, and strong against aggressive hands. A pure combo deck like Outcome or DPS might use this as a better Hurkyl's Recall. I think pushing combo could be a positive effect overall, but I don't know if it's the specific effect you were going for? I feel like it doesn't really do anything for any other deck.
edit: @chubbyrain jinx!