The test being done:

first of all, I bought a "light crossbow" to have as simple a damage range as possible, it had a 9-10 which made number easy to compare.

I unequipped any +x-y damage ring/amulets I had

I unequipped any increased attack speed I had

I bought some cheap jewelry form the ah that had both crit and crit damage and no other dps-relevant stats.

statwise, with/without the jewelry the relevant data are:

set 1 : 1.1 aps, 9-10 weapon damage, 1268 int, 17.5% crit chance for +50% damage, totaling to a paperdoll dps of 155.46

set 2: 1.1 aps, 9-10 weapon damage, 1268 int, 25.5% crit chance for + 136% damage, totaling to a paperdoll dps of 192.53.

all tests were against a single slow zombie in act 1 inferno, for the purpose of reliability on damage over time effects ( blizzard, venom hydra) I stood still and took the beating under crystal skin.

All results were consistent in increased damage with the higher crit chance/crit damage gear, all other things being equal ( no +%damage modifier of any kind, no followers)

you saved me a lot of work there, tho i'd like to know your observations as to how the crit / critdmg affected the numbers of the hydras, since i always only saw what seemed to be + 50% crits on my arcane hydra.

Has anyone tested their furthur? I run venom hydra but have no crit damage/chance gear.

this will make your min damage= max damage (as long as you use the right weapon) .. All your offensive abilities will do constant damage ... Much easier to test...

And no, I have not tested this, but I have played in inferno for over 100 hours and would easily spot the change in damage if these moves actually hit critically.

Some of it can be explained with the weapon damage range ( I have a ~400-700 sword plus a ~100-350 offhand, so base damage variance is ~500-1050) but not all.

you saved me a lot of work there, tho i'd like to know your observations as to how the crit / critdmg affected the numbers of the hydras, since i always only saw what seemed to be + 50% crits on my arcane hydra.

I'll have a look at what numbers I'll see with an arcane hydra once I get back from work, should be easy to see with +246% crit damage

I'll look deeper in the venom one

dpswise, stats are:

set1 : 1394 int, 29.5% crit, 129% crit damage, paperdoll dps of 119.87

set2: 1382 int, 29.0% crit, 183% crit damage, paperdoll dps of 131.84

target mob: some quill fiend in the "old ruins" zone, they were stuck so they made it easy to stack the hydra without losing ticks

set1 hydra max tick experienced: 89, this for about 7-8 hydra recasts, switched item when the quill fiend got to 50% hp

set2 hydra max tick experienced: 112, note that the item switched was a single amulet, I lost both a bit of int and 0.5% crit to gain 55% crit damage.

further tests: single small zombie, aggroed it and stood still while a waiting for a single hydra to do it's full duration damage, calculated the sum of all the damage it did for that single cast

set1 hydra damage : 2361, 2326, 2319, 2300

set2 hydra damage : 2340, 2371, 2208, 2319

I don't think we can have a conclusive answer, but sicne I find it unlikely that it behaves differently from the other hydras, I find it likely it doesn't apply crit damage (<-sad)

a recheck on blizzard : 210% of weapon damage at 1382 int and 6-6 damage range would be ~186/7 damage over the full duration.

if crit damage was 50%, "average" damage expected for 29% crit chance would have been

187*0.61 + 187*0.29*1.5 = ~195, highest damage attainable assuming all cirts would have been 187*1.5 = ~280

for sake of completion, the familiar (no rune) hits for ~17-19 and crits for ~48-53, so it is affected by critical damage

at crit damage of +183%, expected average damage per full cast is 187*0.61 + 187*0.29*2.83 = ~267, with highest possible being ~529

single cast full duration damage results : 295, 318, 284, 316

That sucks, I was stacking crit and now half my dmg doesn't benefit from it.

I used the following setups:

Setup 1: 2.5k dps, 50% crit damage, 21.5% crit.

Setup 2: 2.5k dps, 93% crit damage, 21.5% crit.

Lightning hydra result shows that both setups deal similar crit and non-crit hits. The crit hits are dealt at 50% increased crit damage. Venom hydra result is the same: the two setups produce the same max stack ticks (1700~) on a stationary enemy.

The result confirms what was previously known: your hydra's damage is normalized to your character sheet dps, disregarding your other stats. The only new discovery here for me is that hydras that can crit only crit for 50% additional damage. However, their base damage is still based on your character sheet dps, and crit damage affects this dps number.

Conclusion: your character sheet dps determines your hydra dps.

EDIT: A more thorough and interesting way to test this would be to use 3 different setups at the exact same dps, one achieved mostly using crit damage and crit chance, one achieved using no crit damage, and the last using no crit damage or crit (all IAS and/or int). In the case of venom hydra, all three setups should produce the same tick damage. Other hydras that can crit should give different per-hit numbers accordingly, both crit and non-crit, since their dps should be the same.

Thank you for this

You could empty your arcane power and then see if hydra ticks actually increase it. If they do then hydra would "actually" crit

OK so crit chance DOES work on hydra and blizzard, but do they trigger critical mass?

If they do, does this have any hidden modifier?