Avatar of Wuluxar
A Primer on Snapshotting(1)Category: PTR FeedbackNovember-19-2015 9:12 AM PST (8 years ago) Go to Blizzard forum post
Below is a post from Wyatt Cheng, explaining the snapshotting mechanic:

I want to clarify a few things about many recent discussions of snapshotting and make sure we’re all on the same page as to what that means.

Snapshotting is very fundamental mechanic in Diablo III that allows the game to work correctly and according to player expectations most of the time. It's a bit like having electricity in your home; you never really think about it when it's working correctly, but you sure do notice when it's not! By and large most skills should snapshot the state of your character at the time your ability is used unless there is a good reason not to. This is what allows you to cast Rend just before Wrath of the Berserker expires and retain the damage bonus. You hit that monster really hard didn't you? Not only does Rend snapshotting the damage at the time the ability is cast allow for skilled players to time their abilities for maximum effect, it's also what you would expect the skill to do mechanically—bleed a lot because you hit really hard! As another example, you wouldn’t want to have a character equip a very high-speed dagger, cast a bunch of projectiles, and then switch to a high-damage two-hander to artificially boost your damage by using the damage of your character at the time the projectiles landed. Projectiles should do the damage the caster had at the time the projectile was fired. They need to snapshot.

All of this is the intended and necessary design of Diablo III.

This brings us to the confusion we see when people refer to snapshotting as if it were a global bug. There’s a huge, important difference. While most skills should snapshot, some skills and items with long or persistent effects should instead update continuously. To use my analogy from earlier - sometimes the light switch doesn't work and you REALLY notice.

Whether a skill is subject to snapshotting is not a black and white decision either. If I cast a 5 second Rend, I expect it to do damage based on the strength of my character at the time that I cast it. What about a 12 second Haunt? Should that damage be determined at cast time? What happens when that Haunt lasts 5 minutes? Rain of Vengeance snapshots your damage at the time you cast it, but what if we were to make a Legendary that made Rain of Vengeance last forever? No, we're not doing that, but if we did then we would probably want to make it so that each Rain of Vengeance cast while that Legendary is equipped updates continuously. There are some skills where snapshotting is debatable, and there’s a tipping point over which you no longer want to snapshot because of negative gameplay that results. Huge thanks to those who have detailed instances (such as Bane of the Stricken) where a change is needed.

As you can see, general discussions about snapshotting don’t help as its existence is an important element of the game design. As you continue to play on the PTR and experience new item and skill behavior, please let us know when you encounter specific skills or instances where you feel a skill should update continuously rather than snapshot at the point of cast. Thank you for helping us make patch 2.4 awesome!

Examples brought up:

Bane of the Stricken - Updates now with your overall attack speed but NOT with the attack speed of specific skills (bracers of the first men). This is something we're investigating but no promises and we may leave the design as being based on your overall attack speed.

Iron Maiden - Fixed in PTR Patch 1.

Uliana's with Power Pylon - Under investigation

Chantodo stack speed - Under investigation
Feedback for Diablo Somepage