4e:
* The WARLORD
* Power Sources and Class Roles: This led to 4e having the gumption and vision to pull the trigger on something that not even 2e could commit to doing : removing all divine magic classes from Dark Sun.
* Class parity and balance
* Scene/narrative-based mechanics (AEDU)
* Martial classes had interesting and thematic tactical choices that were typically privileged to magic classes.
* Monster design: minions, monster roles, cool monster mechanics, etc.
* Tiers of play including epic destinies
* Saves as defenses
* Rituals