For starters, it can be your commander, ensuring you always have access to its mana rebate ability
While it feels a little underpowered in places, the general concept is an interesting one
For example, if three Fraying Sanity Auras are attached to one player who had four cards put into their graveyard this turn, X will be four for the first ability to resolve, eight for the second, and sixteen for the third
Note the pull rates refer to your chance of pulling each card in a regular pack, and not in a rare pack (or god packs, as some fans call them).
That's the back of the cards
The former is a 2/2 with flying and can cast a legendary, artifact (or Saga, but there are none here) into a free 3-drop or less creature card like Esper Sentinel or Zulaport Cutthroat