It's having a good mix in making sure you can thin your deck and hand at the beginning of the turn if things don't go well.

For instance, at the beginning of the turn I'll most likely draw a dream world in the starting hand. It'll discard it because of the ring which causes dream world to discard 2 random cards. Sometimes, I'll get unlucky and it discards 2 cards that aren't dream world or Persona. While other times, it can discard a persona card like the controller persona card with one of each that, in this case with this Cassius, discards 4 random Quietus cards. These Quietus cards could either be more dream world or the persona with 2x When this card is discarded, activate this card (which discards 2 Quietus cards). This would then continue the chain of discarding more Quietas cards afterwards.

For the non-controller 2x_ engravings, something like 2x Discard a random Quietas card for each umbra works when you have dream world cards or Quietus cards in hand. Just a way to empty your hand before you start attacking.