[SPOILERS] Yet another achievements-help request

Sugary

So, I've got three achievements missing.

Trivium.
Perform a task worthy of the Terrible Trivium.
Got absolutely no idea about this one, guess I've just missed something.

It wasnt me!
Convinced Duke Belt that you weren't responsible for Skie's murder.
Which quests must be resolved for this one and how?
Maybe specific class or stats required too?

Grim deeds to come.
Its bugged as far as I understood and nothing can be done at the moment.

Vbibbi

Trivium you get in the underground river caves. Talk to the guy when you first enter the caves where the crusaders have their supplies. You'll ask him if he needs help, he asks you to move some grain sacks from one box to another. Finish the quest line and you'll get the achievement.

It wasn't me! requires that you successfully defend yourself when on trial in BG. So you have to have done enough deeds to convince Belt that you couldn't have killed Skie. There are a good number of options and you have to pick four in order to be set free.

If you're a paladin you can use that as a reason why you're innocent.
If you're a hero (18+ reputation?) you can say your good character proves your innocence.
Freeing the eyeless Bhaal priestess gives you an option, whether you tell her to reform or continue evil deeds.
Whether you poison the food supply in Dragonspear or not gives you another option.
If you heal the sick soldiers in the coalition camp that's another option.
If you offer up yourself instead of your companions to the fiend in Avernus, that's an option.

Those were the six options I had in my playthrough. There might be more. But you only need four.

Grim deeds to come is still bugged, unfortunately.

Sugary

Ah, thank you very much, those two worked fine.