This article was written by me, Nick, and Brian. If you have any questions, please PM me or ask them in this thread!
With the start of the next challenge leagues we're introducing some major changes to game balance. In particular, we are removing all snapshotting mechanics.
Snapshotting currently allows players to obtain the benefits of one set of items, passives or gems by casting a skill that locks them in (by taking a snapshot of their character with all those things active), then swapping to another configuration so that they have both sets of benefits. For example, a player equips an Alpha's Howl helmet to reduce the mana reservation of an aura, casts the aura with this lowered reservation, then removes the helmet. They now have a cheaper aura active and can equip a different item into their helmet slot.
The majority of snapshotting is used in minion builds. Support gems and minion-augmenting items are swapped in and out to summon large numbers of unusually strong zombies and spectres without worrying about any of the item downsides. Raising a spectre and swapping out supports to raise a spectre of a different type allows spectres raised from the same gem to benefit from an entirely different set of support gems. This process can be incredibly complex and time consuming, as demonstrated in our recent Build of the Week video.
Snapshotting works for aura-driven builds as well. Using a combination of Reduced Mana gems, items and reservation passives, players can run an unintended quantity of super-powered active auras. We've seen this used to a particularly high degree around the challenging Atziri fights.
Righteous Fire is also regularly used with snapshotting mechanics to bolster damage. The skill is used without detrimentally affecting the player's survivability, since all the damage boosting items are swapped out once it has been cast.
Removing snapshotting results in a better game
Though players have been incredibly creative in finding ways to use snapshotting to grow powerful, it has been an issue for a long time. Snapshotting isn't specifically against the rules, but the imbalance it causes among players is not good for the general health of the game. It's also pretty unintuitive for a portion of an item's effects to stay active long after the item has been removed.
Snapshotting is a bit of a lose-lose mechanic. Players using it have to go through tedious setup to make their builds work, time they should be spending slaying monsters and having fun. Players who don't use snapshotting often feel they are underpowered by comparison. They're usually right.
Snapshotting has also stifled design for a while. When we want to add a new skill or item to the game, we have to assess whether it's abusable with snapshotting. Mon'tregul's Grasp, for example, is a flavourful, powerful item that asks players to choose between a few super strong zombies or lots of normal ones. With snapshotting, that choice doesn't exist. Players who use Mon'tregul's Grasp to snapshot are straight-up stronger than players who don't. Snapshotting abuse of things like Mon'tregul's Grasp has prevented several planned cool mechanics and items from finding their way into the game.
Same skills, different behaviours
Currently, minions and buffs are internally handled as separate things. With our August mini-expansion, we're handling all ongoing effects from skills together, so they'll immediately feel the changes to gear, skills or passives. This means no more using Alpha's Howl snapshotting to run multiple reduced mana auras.
Under the new system, removing an aura mana reservation item will terminate its effect. If this means you can't afford to keep all of your auras active, one of them will turn off. We deal with changes to maximum minions, minion strength, gem levels and more in the same way.
There are some other interesting side-effects of how we're handling skill information in 1.2.0 that will allow us to develop convenience changes down the road for players.
Areas of the game affected by the changes to snapshotting
All minions created by Dominating Blow, Summon Skeletons, Vaal Summon Skeletons, Summon Raging Spirit, Raise Zombie, Raise Spectre, Animate Weapon and Animate Guardian will dynamically update to all stat and support gem changes. Minions generated with a set level will not increase in level when the gem enabling them levels up. If such a gem levels up while you have minions active, the change in minion level will only be reflected in newly-raised minions. Minions will respawn when you enter a new instance, so their levels will update to match the current higher level of the gem.
Your Animate Guardian's equipment will persist on logout, but due to the snapshotting changes we're making, it won't immediately appear when you leave town. Players will now be able to retrieve their guardian by targeting a blank space of ground and casting the Animate Guardian skill.
Totems, Traps and Mines:
As with minions, the stats of placed traps, totems and mines will change dynamically as players equip or unequip gear and support gems. If you've placed any traps, mines or totems augmented by support gems, unsocketing any of the gems will destroy the trap, totem or mine.
Any passives, items or support gems that change the reservation cost or properties of Auras will be immediately reflected. Auras you can't afford to keep active will fall off. Don't worry, changes in aura reservation while Blood Magic is active will not kill you!
By design, Righteous Fire is meant to persist, whether or not you lose the skill. The theme of the skill is that you burn to death! As a result, if you unsocket the Righteous Fire gem, the effect will persist, but will no longer update with changes to support gems as there's no skill gem for them to support. However, if you then make changes to your gear or passives that would affect the skill, it will still detect this and change its effectiveness accordingly. If you resocket the Righteous Fire gem in the same slot, it will begin checking the support gems again, and change the effect to match.
Like auras, Tempest Shield's cost and effectiveness will change dynamically with changes to passives, support gems and items. It will fall off if you can't afford to keep it active.
We're currently looking at every skill listed above, as well as some items and passives such as Blood Magic. Don't expect every skill to be buffed or changed - we're currently pretty happy with the state of several of them. When we deem changes necessary, we may roll them in with general adjustments to the passive tree.
What took so long?
We've wanted to fix snapshotting for a while, but doing it properly was a pretty big task. It involved a lot of back-end programming work and it has huge balance implications. The impact of fixing snapshotting on existing player characters dictated that we wait for the period between leagues. It's not our intention to disrupt the progress of players in the middle of a challenge league.
Though the fix to snapshotting means that some previously-abusive builds will lose some firepower, the end result is a healthier game for everyone. The changes mean a cleaner, more sensible experience, with more avenues for interesting skills and itemization. In the long run, even those who regularly used snapshotting will benefit. They will no longer feel obligated to spend many tedious minutes setting up a snapshot, for fear of not maximizing their character's potential.