22. The first appearance of Save vs Abilities
From page B60:
As far as I know this is the first time this mechanic appears in a D&D rulebook. I believe, however, that either this mechanic or other similar mechanics had appeared in some adventure modules prior. This adds a very simple way of handling things outside the other mechanics of the game. I use save vs. abilities rather infrequently myself preferring to use derivatives of other mechanics already in the game such as using the same idea as the open door mechanic (2 in 6 with ability modifiers) for other ability checks, the listen or spot secret door checks for other "perception"-like checks, or my favorite - the 2d6 reaction roll.
The key part of Save vs Ability is the header, "There's always a chance." As a 10-year old learning the game this was the key lesson I gained from this section. The mechanic doesn't really matter - giving the PCs a chance to succeed at whatever crazy actions they may attempt does.