Did an experiment with a 100 life per hit weapon with various skills to see how much benefit each skill gets from the listed value, as a "hit" is a little ambiguous. WIP

/tick - per tick, or each time the skill does damage for a Damage Over Time spell. The amount of ticks you get for the duration of the skill is dependent on weapon speed.
/enemy - per enemy, for Area of Effect spells. Each enemy hit by the spell is counted.
/cast - per cast, generally for multiple projectile spells. This is the total potential the spell can leech assuming every projectile hits something.
STACKS - This skill will stack with itself for the DOT portion, thus your spells can overlap and you will get tons of hits. Some spells like poison dart poison damage stack with themselves, but the additional ticks don't count as hits for life gain, so this will only work on skills that count /tick.

Primary Skills:

Poison Dart - 200%
Splinters - 33%/dart (100%/cast)
Numbing Dart - 200%
Spined Dart - 200%
Flaming Dart - 100%
Snake to the Face - 200%

Corpse Spiders - 16% for each JAR hitting something. Individual spider hits do nothing. Also nothing if you miss with the jar. Unfortunately makes a mediocre spell even crappier... I originally started this because I thought per hit life leech would be great with spiders.
Leaping Spiders - 16%
Spider Queen - 30%/enemy/tick
Widowmakers - 16%
Medusa Spiders - 16%
Blazing Spiders -

Plague of Toads - 66%/toad (200%/cast)
Explosive Toads - 66%/toad (200%/cast)
Toad of Hugeness - 0%
Rain of Toads - 50%/enemy/tick STACKS
Addling Toads
Toad Affinity

Firebomb - 66%/enemy
Flash Fire - 20%/bounce (140%/cast)
Roll the Bones - 22%/enemy
Fire Pit - 66%/enemy/tick STACKS
Pyrogeist - 33%/projectile (this thing shoots out a lot of little fireballs, I didn't count them)
Ghost Bomb

Secondary Skills:

Grasp of the Dead - 16.5%/enemy/tick
Unbreakable Grasp - 16.5%/enemy/tick
Groping Eels - 16.5%/enemy/tick
Death Is Life - 16.5%/enemy/tick
Desperate Grasp - 16.5%/enemy/tick (probably stacks, but you only get to overlap once, for 2 seconds)
Rain of Corpses - 

Firebats - 16.5%/enemy/tick
Dire Bats - 33%/enemy
Vampire Bats - 25%/enemy/tick?
Plague Bats - 33%+? This one is hard to test because I have very little mana. it does increase the longer you apply it.
Hungry Bats - 33%/bat
Cloud of Bats

Haunt - 100% per target hit and none on the DOT. If it acquires another target after the first one dies, it will count as another hit.
Same for all runes - Not confirmed, but very likely

Locust Swarm - 33% per target, same as haunt. Each time it spreads it will hit, but no bonus from the DOT.
Pestilence - 33%
Devouring Swarm
Cloud of Insects
Diseased Swarm
Searing Locusts - 33%

Others:

Zombie Charger - 50%/enemy
Leperous Zombie - 50%/enemy/tick
Undeath - 50%/enemy
Wave of Zombies - 8%/zombie/enemy/hit - I'm not sure, but it seemed like these guys can hit the same enemy more than once
Explosive Beast - 50%/enemy
Zombie Bears

Post by Elegy

Spirit Barrage - 100%
Spirit is Willing - 100%
Well of Souls - 33% per soul (4 total)
Phantasm - 25% per enemy per tick
Phlebotomize - 100%
Manitou

Fetish Army - 0%
Fetish Ambush - 40% on cast if it hits a mob (Unsure about this one!) 

Summon Zombie Dogs - 0%
Rabid Dogs - 100% per enemy per tick of the DoT (With a single ZD attacking an enemy, I noticed a 200% tick right after every attack, which may mean the DoTs were overlapping.) STACKS
Final Gift - 0%
Life Link - 0%
Burning Dogs - 100% per enemy per tick of the AoE aura (STACKS per dog)
Leeching Beasts - 

Sacrifice - 33% (per enemy? These were tested on single targets.)
Black Blood - 33% (per enemy?)
Next of Kin - 33% (per enemy?)
Pride - 50% (Glitch? per enemy?)
For the Master - ?? (appears to be glitched and healing me for LESS than it should, should have healed for 3x 3154, but only got back 9260)
Provoke the Pack

Gargantuan - 0%
Humongoid - 0%
Restless Giant - 0%
Wrathful Protector - 0%
Big Stinker - 100% per enemy per tick of the AoE aura
Bruiser - 0%

Wall of Corpses - 16% per enemy per tick 
Barricade - 20% per tick
Unrelenting grip - 16% and 33% per tick
Creepers - saw 16% and 33% per tick on the wall, the adds provided no ticks.
Pile on -
Dead Rush -

Acid Cloud - Very tricky and needs a lot more testing! I think the Acid Cloud and Acid Rain might be effected by distance from the center. Appears to be 166% near the middle, down to 16% at the edges
Acid Rain - Most ticks around 280% near middle
Lob Blob Bomb - Blob ticks around 33% but saw 16% and 50% as well.
Slow Burn - Ticks of 16%, 33%, and 50%
Kiss of Death - Ticks of 16%, 33%, and 50%
Corpse Bomb


On Sacrifice - I was getting 16% per enemy
On Acid Rain - These numbers are all over the place, but they are always a multiple of 40% for me, so I'm just gonna say the base is 40% and it ticks A LOT faster than other spells.

Non Damaging Skills (Soul Harvest, Horrify) - 0%. However, SH runed for damage does get 25% per target up to 5.

Note on pets - Zombie dogs and gargantuan hits will not give any life. However, flaming zombie dogs aura is 100% per enemy per tick per dog!! I don't have big stinker yet but I imagine it is the same. Potentially huge, but good luck keeping them alive...

vs Life Leech % - Leech % is pretty straight forward. The more damage skill does, the more you will leech. As you can see, some skills benefit much more than others from life per hit (flaming zombie dogs, flash fire), while others benefit more from leech % (spiders, locust swarm), so which to get really depends on your build and what skills you use.

Fierce Loyalty - Life on hit does NOT benefit your pets. You will still get the life though

Other on hit effects - Flaming Zombie Dogs and Big Stinker WILL proc on hit effects (fear, blind, ect) via their aura, but NOT on their attack. This is pretty awesome, if you manage to get some 10% combined stun/fear/freeze and have 5 aura pets surrounding something that isn't immune, it WILL be more or less permastunned.

05/22/2012 04:27 PMPosted by Eshi
actually, yes, I think they do. I have a 1.9% fear on hit helmet and rarely proc'd it until I changed builds using this thread. Now I trigger fear TONS of times, it's ridiculous. I'm going to start loading up on x% on hit enchants.