As the title says, the game won’t let you cast the card. It doesn’t show up red, but it refuses to cast. I have tried this both on an empty board and with creatures on my opponent’s side, both times with opponent avove 40hp, and both with cards in hand.
I know no one uses this card, but it is a bit disappointing.
Did you also have creatures out and other cards in hand?
The card has 4 requirements to cast:
You have creatures out
Your opponent has creatures out
You have other cards in hand
Your opponent has other cards in hand
That’s why nobody uses it
If I remember correctly, Urza’s Ruinous Blast also has the same problem: If I do not have a non-historic creature or support, it refuses to be cast even if opponent has non-historic cards.
In other words, Ruinous Blast and Fraying refuse to be cast if you have nothing to lose. Boo, boo, they took the lesson of paper Magic’s Balance way, way too far.
Ruinous blast is a legendary spell. You have to have a legendary creature in play to cast it, just like the other legendary spells.