For years, Single Player gamers were locked out of "Ladder-Only" items (such as the Rune Word Spirit or Insight ) because the game restricted them to online seasonal play. Modders eventually unlocked these for single player, but obtaining the required runes (like Jah and Ber) was statistically improbable for a solo player. Item packs democratize access to these build-defining items.
Some items have errors, like Tyrael's Might showing +100% requirements instead of -100%. Old Mechanics: For instance, the Hellfire Torch