Pen Finger : 2 mana.
Deck of Lunacy : 5 mana
Libram : 4 mana so less opressive in the early game. In mid-late game it still free.
Spring Water : 6 mana
Tickakus : 8 mana
So just kill every single card because you have the mental fortitude of a toddler and can't handle losing to them once in a while?
Nerfs aren't meant to straight up kill a deck. Nerfs are mean to reduce the power of the deck (most of the time). Mage, paladin and warlock are strong but barely game breaking enough to increase the mana cost of their cards by 3. Actually just changing spring water to 5 mana might be enough. Paladin you could just nerf hand of hadal to 3 (staple in every paladin deck), sword to 3 and aldor intendant back to 2 mana.