You remember the patch when Centaur got reworked and got his totally overpowered ultimate (it used to stun with more damage and a lower cooldown iirc) and Drow got her new aura which basically gave you free ranged mega creeps permanently? The back toning on these two heroes is the most I remember, but then again I hadn't been following the changelogs much 4 years ago so I probably missed many things back then. Also 1000 Phoenix reworks.