I picked up a small charm with +1 Max Dmg, +17 Attack Rating, +6 Poison Dmg over 3 sec. The interesting thing is when in my inventory, it actually decreases my damage. AR does increase. Is this a bug or some mechanic I’m not understanding properly?
Without charm
Berserk: 3445-6002, 6724 AR
Whirlwind: 2637-4721, 5341 AR
With charm
Berserk: 3402-5970, 6831 AR
Whirlwind: 2594-4685, 5426 AR
All my other Max Dmg charms seem to be working properly.
It’s not about the +1max damage part, it is about the +6 poison damage part.
It’s quite complicated how poison damage is added in this game. For example the duration of poison damage of multiple affixes is added together. The way multiple instances of poison damage are added, the damage per second can in fact be reduced. I’m not sure if this is to be considered as a bug or as working as intended.
To echo the above, its the +poison damage that is making the value show lower as if you have other sources, it does some calc’s with it (too lengthy to explain here but a little research will give you the answer).
Do you have other sources of poison damage like other charms, venom grip, etc?
Poison damage calculation is complicated and character sheet is often wrong. Because 6 over 3 sec is low poison bitrate and low duration, it will only slightly increase your total bitrate but usually reduce your duration, affecting sheet damage. If you look at your deltas, your min damage drops more than your max. This makes me believe you are getting that +1 max but, as I mentioned, you’re doing slightly less poison damage over however many seconds.
I do have +204/6 poison from the IK set (on the maul). Wonder if the longer duration on that is conflicting someway with the 3 sec on the charm. It’s such a small amount I’d be getting from the charm, so its just gonna sit in the stash for now.
Thanks all for the insight, looks like I need to brush up on how poison damage gets calculated 
Ya calc’s for D2 can get very weird very quick.
Yeah, that’s it. Your maul does 34/second poison but that charm is only 2/second. The rates get added to 36/second but then the duration gets averaged down to 4.5 seconds. This takes your 204 poison damage down to 162, a loss of 42 which is roughly what you lost on your char sheet’s min damage. Max damage was less affected because of the +1 max on the same charm. Also, if you ever use grief or another source of the assassin skill venom, all poison damage gets cut off at 0.4 seconds, mostly invalidating any sources of long duration poison on charms or gear.
so on my paladin i have greif and some sc poison damage and my char sheet damage drops once i attack. is this just the calc not reading correctly or am i doing less damage?