Context - We're three weeks into the Scholomance Acadamey Expansion. Kael'thas Sunstrider, who was broken before Day 1, has been fixed, but no other nerfs for Standard have been introduced (Mindrender Illucia was mostly for Wild).
HSReplay has the Tier 1 decks as Libram Paladin (58.1%), Face Hunter (57.4%), Stealth Rogue (57.2%), and Aggro Demon Hunter (55.9%).
My suggested nerfs:
Libram of Wisdom - Change the cost from 2-mana to 3-mana. This wouldn't affect the end-game power of the card or of Lady Liadrin, but would make for a much fairer early-game and mid-game. At first I speculated on changing stats or discounts of Aldor Attendant or Aldor Truthseeker, but their stats and effects are generally balanced for the other Librams. You want wisdom? You need to study harder and longer first.
Voracious Reader - Change the cost from 2-mana to 3-mana. There's nothing to over-think here. Make the card slower. Make it harder for a player to empty their hand on the same turn they play this. Make it come down later when the opponent can more easily deal with it. We all knew this card was too good as printed, and it's overdue for a nerf.
Secret Passage - Change "Replace your hand with 5 cards from your deck" to "3 cards." The Soularium was an excellent legendary spell. This draws more, is more consistent, and has no down-side. It's barely RNG to use this card to search for a game-winning Eviscerate or Sinister Strike. Making this change won't alter a single deck-list in current Rogue decks, but would hopefully shave a few tenths of a percent off their win-rate.