This is such a strange card.
It works like this:
So, it basically turns off any card draw spell, making draw into cycling. But it also turns Wheel of Fortune, Timetwister and (most importantly, since it costs 1 and is unrestricted) Winds of Change into symmetrical Mind Twists.
Then there is a lock with one Howling Mine and two Chains of Mephistopheles when your hand is empty. What happens is that you draw a card, then you would draw the extra card from the Mine, triggering the two Chains, making you discard first the one card you have, then mill a card instead. So the only thing anyone could play at this point is an instant if it’s the first card you draw each turn. Not a true lock against a deck with Disenchant, but likely to turn everything off for a long time, and then you can use something like The Rack to win. The only problem is that you need to assemble two Chains and a Howling, and you can’t tutor for or copy the Chains in any reasonable way (compared to, for example, if you needed two Howlings, in which case you could use things like Copy Artifact and Transmute Artifact to find more of them).
But with Scryings, that is no longer a huge issue. Take a look at this:
Yes, then the lock is just having one Chains and one Anvil in play, with no cards in hand. Much more reasonable. I could see Chains decks being somewhat competitive now. They would likely want to have a low mana curve so they can empty their hand before going for the symmetrical Mind Twist with the Chains + Winds combo, a bunch of instants that you could play under the lock, maybe some way of finding the pieces which is harder since card draw like Sylvan Library or Lat-Nam’s Legacy is horrible with Chains. And for the kill, either The Rack or Millstone. If you have smaller creatures too, probably the Rack way is better. This could be built in lots of ways, as the only mana constraints are single black for Chains and single red for Winds.
Anvil is also a weird card with a number of somewhat unconnected abilities and synergies. First of all, it’s somewhat like a Howling, but with a smaller downside in that it’s not as bad for you when the opponent gets an activation and then just Disenchants it, whereas if you want it out, you probably can have cards to discard. In this way, it could potentially work as extra copies of Howling Mine for a deck that would benefit from that, maybe Twiddlevault or Underworld Dreams combo.
Then there is the discard synergy, which isn’t very useful in Old School currently but could maybe work in some kind of Reanimator strategy or similar. Who knows what else Scryings might bring?
And then there is the Library of Leng clause, which is even symmetrical. This could mean trapping somebody under Black Vise, potentially making this useful in the Vise/Ankh Atog decks. Or just having it as a more useful Library of Leng in the Land Tax decks, as the looting ability would likely benefit you more than your opponent since you’re the one with a hand full of basic lands.
There are probably other synergies I’ve missed too. Get brewing!