Like most Magic: The Gathering cards, the value of Diamond Weapon depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Final Fantasy)
You can force the issue with the activated ability, which combined with an indestructible effect lets you mow through all your opponents' boards
Grade: D Mental Agony is not a good card
Its abilities lets you play snow cards from the top of your library, which means that scrying and surveilling are super useful here
No one will use pinpoint removal on a Wall
According to comments from Magic's head designer Mark Rosewater in May 2026, the "new normal" from next year onwards will be a "three and three" split between Universes Beyond crossover sets (like Lord of the Rings and Teenage Mutant Ninja Turtles) and sets based in Magic's own fiction (like Lorwyn Eclipsed and Secrets of Strixhaven)