So with all the cards being able to cast condition juggling between making a card uncastable (crossed out and red in hand) and not actually casting (full of mana, all white and shiny, but not actually casting), here are two issues from memory:
(MAJOR) Anguished Unmaking no longer casts if there is no support on the opponent’s side. I did not try to reproduce this with only supports for the opponent, but I can confirm I had an opponent with creatures, the confirmation box popped up, I chose “CONFIRM” several turns, but nothing happened.
(MINOR) Vona’s Hunger is not crossed out from hand if the opponent has no creatures onto the battlefield, but it is not cast.
I am sure there are other spells in this situation so if anyone else has examples here (from this specify category) let’s compile a more comprehensive list.
//Edited Title -Brigby