What happens if I play "Judgement of Verena" and the "Great Book of Grudges" is in play?

a) "GBOG" triggers when the unit it is attached to enters the discard pile.

b) "GBOG" doesn't trigger because it is destroyed before the unit it is attached to enters the discard pile.

c) Another answer.

Thanks a lot in advance!

Since the cards are all destroyed simultaneously, I'd say the most likely answer is b.

The units/supports are destroyed simultaniously yes. But isn't the same way like Troll vomit, that you can choose in which order the cards go to the discard pile? This way you would just have to get this unit into the discard pile first and the book would trigger, wouldn't it?

Or wouldn't it trigger because it's destroyed too? xD Hach...

If you can choose which order they go into the discard pile, it wouldn't be destroyed simultaneously would it? From the previous ruling on dwarf rangers, you don't get to choose. They're all destroyed at the same instant.

You can choose the order in which they enter the discard pile, but they still all end up there at the same time. Same deal as with the Dwarf Ranger vs Troll Vomit, DR can't hit you for 1 dmg for each D unit that hits the discard even if you put the DR on top, because it was destroyed at the same time.