6.88d2 was the before 7.00 (December 2016). Many pros (Miracle-, SumaiL, Arteezy) have since called this the most balanced patch in the game's history—where virtually every hero had a 45-55% win rate in high MMR.
was a bugfix and micro-balance release. By this point, the meta was considered incredibly mature. Instead of sweeping changes, IceFrog focused on trimming power from the most oppressive pub & pro picks (Shadow Demon, Arc Warden) while fixing critical mechanical exploits. 6.88d2
Version 6.88d2 introduced critical balance triggers to prevent game-breaking combinations, such as specific interactions involving the "Rearm" ability. By this point, the meta was considered incredibly mature
Here is a focused write-up on .
It looks like you are referring to (the original Warcraft III mod) patch 6.88d2 . This was a minor, yet highly refined, balance patch released during the long 6.88 era—right before the major shift to 7.00 (The New Journey). Here is a focused write-up on