I did a lot of playtesting with new Lavinia when she was spoiled and I've found a lot of problems with the Knowledge Pool "lock". The biggest issue is that she does not stop commanders from being cast, meaning value engines like Yisan and Vannifar, or even graveyard casters like Kess and Dralnu can still operate through the Knowledge Pool . The RIP/Helm combo gets really telegraphed as well, considering that you need to cast the combo piece to give it to the pool, and then cast another spell to cast it, but there's nothing stopping an opponent from casting an instant and sending the combo piece to your graveyard unless you have a Silence or Grand Abolisher effect up or you cast a spell in response to your instant. That doesn't feel very ideal considering that you may need to cast three spells or more just to get a combo piece through. I'm not saying your deck is bad by any means, these are just apparent flaws that I've noticed in my build and every one that I've seen and you have to be really careful about what you can and can't do when running an oppressive effect like this because it can turn out to be a detriment.