Path of Exile Content Update 2.1.0
As the amazing year of 2015 is drawing to a close as of this writing, it seems that Grinding Gear Games is not done with improving Path of Exile for the year just yet. There had been a lot of new things that were added in the game already, but the developers seem to have perfection and evolution ingrained in their manifesto. This new update is yet another step towards that seemingly unreachable but noble goal.
Content Update 2.1.0 is basically a set of balance changes and additions to the game that may be a long time coming. It had been in development for quite a while, amidst all the expansions and other updates to the game throughout 2015. Grinding Gear Games stated that the decision to make this update was made to facilitate more interesting choices in character building by having fewer "incorrect" choices.
A big part of doing just that is by raising the power level of underused or underpowered game mechanics rather than just nerfing the properties of more powerful mechanics. This is pretty much the act of "balancing up," which is advocated by a lot of game designers and fans. This is done in order to make sure that pretty much everything in the game is interesting, making for more exciting play as a whole.
The rework of the Poison system spearheaded this update as it was announced and implemented before the announcement of this content update. As for the rest, do take note that they readjusted mechanics and not just skills, so these changes have a far-reaching effect on the whole game. Many of them were buffed, while a few were nerfed in some way, but mostly not in a big way. The result is something that makes Path of Exile more different than it was before.
The following got straight-up buffs: Spell Damage Progression, Melee Splash, Leech, Mana per level, Melee mana costs, Point Blank, Bows and Bow skills, Raise Zombie, Magma Orb and Arc, and Searing Bond.
The following POE items got straight-up nerfs: Surgeon's Flasks (but not retroactively), Poison Arrow (due to new passives and supports that now work with it), Incinerate, and Cyclone.
There are some that got both buffs and nerfs at the same time, with each adjustment affecting how they perform in the early and late game. For instance, Flame Totem got an early game nerf and a late game buff, while Summon Raging Spirits got an early game buff and a late game nerf (the latter only for certain characters). This is to make sure that there's no point in the game when they're not viable or less effective.
The sustained effectiveness of skills and mechanics in action role-playing games has always been a point of contention in the genre. We've seen plenty of games where the skills gained at earlier levels become nothing more than wastes of space on the skill tree later in the game, as if they were acquired only to reach later level skills.
That is something that Grinding Gear Games is trying to avoid (same with Path of Exile items), and they're doing what they can to mitigate that in this Content Update.