No, the above is not quite correct. 

I guess this is a somewhat complicated topic that really needs a writeup.  For now, lemme just give you a nudge in the right direction.

[AFFIX]
<STRING>NAME:BERSERKER_EVISCERATE
<INTEGER>RANK:0
<INTEGER>MIN_SPAWN_RANGE:0
<INTEGER>MAX_SPAWN_RANGE:999
<FLOAT>DURATION:0
<INTEGER>WEIGHT:0
<INTEGER>SLOTS_OCCUPY:0
[EFFECT]
<STRING>NAME:eviscerate_bleed
<STRING>ACTIVATION:DYNAMIC
<STRING>DURATION:6
<STRING>TYPE:DAMAGE
<STRING>DAMAGE_TYPE:PHYSICAL
<BOOL>USEOWNERLEVEL:true
<STRING>UNITTHEME:BLEEDING
<BOOL>EXCLUSIVE:true
<BOOL>REMOVEONOWNERDIE:true
<FLOAT>MIN:15
<FLOAT>MAX:15
<FLOAT>MINFORCE:0
<FLOAT>MAXFORCE:0
[/EFFECT]
[/AFFIX]
TYPE
This field determines the category of effect.  For Eviscerate, it's DAMAGE which is a flat damage amount like what you see in skills like Glaive Throw, Prismatic Bolt or Eviscerate.

MIN/MAX
These are relative to the category of effect they modify.  Here, they modify the amount of damage this affix deals.  15 is a percentage of the graph (stat line) this effect references.  To find out which graph is being referenced, you need to find 'DAMAGE' in the Effects Editor.  It should be something like MONSTER_DAMAGE_BY_LEVEL.

USEOWNERLEVEL
This means that the 15 in the min/max field is 15% of the MONSTER_DAMAGE_BY_LEVEL graph at the caster's level.  So, you can look at the graph and multiply by 15/100 to figure out how much damage the affix will do.

DURATION
Determines how long the effect lasts.  In this case, it deals bleed damage over 6 seconds.  Durations longer than INSTANT deal their damage per second.  So, this affix deals 15/100(graph@player level) PER SECOND.  That means the total damage dealt is multiplied by this number.

EXCLUSIVE
This is set to TRUE which means only one of these effects with the same name can be applied to a target at once.  The duration will refresh but the damage per second remains the same.  If FALSE, the duration will not refresh for older applications but the damage will stack.


Hopefully others can fill this in more, I need to study.   

Thanks VERY much Gyt! That's more than a nudge actually, and it's very helpful I'll do more reading-up on each field too.

I'll let @RnF  explain them since I'm pretty sure they're item-related.

However, the duration field is irrelevant for skills.  Leave it at 0.  It won't harm a thing.

you have to use different affixes for different target types, unless you dont specify a target type,
then edit the affixes spawnclass targeting,
i would just go with using another affix string over editing the target types inside them though.

Hiyya!

About that "%chance to kill outright" affix I'm using on Tier3 of the Destro "Slash Attack" skill... instead of a %chance, it's insta-killing everything it hits every time

Here's the affix code that's supposed to give a 10% chance to insta-kill...

[AFFIX]
<STRING>NAME:DESTRO_SLASH_KILL
<INTEGER>RANK:1
<INTEGER>MIN_SPAWN_RANGE:0
<INTEGER>MAX_SPAWN_RANGE:999
<FLOAT>DURATION:0
<INTEGER>WEIGHT:0
<INTEGER>SLOTS_OCCUPY:0
[UNITTYPES]
<STRING>UNITTYPES:ANY
[/UNITTYPES]
[EFFECT]
<STRING>NAME:DESTRO_SLASH_KILL
<STRING>ACTIVATION:DYNAMIC
<STRING>DURATION:INSTANT
<STRING>TYPE:KILL
<FLOAT>MIN:10
<FLOAT>MAX:10
[/EFFECT]
[/AFFIX]

In the skill's .DAT, I call it with this...

[EVENT_UNITHIT]
[AFFIXES]
<STRING>TARGET:ENEMY
<STRING>AFFIX:DESTRO_SLASH_KILL2
[/AFFIXES]
[/EVENT_UNITHIT]

It occured to me that I should be targeting SELF (giving myself that %chance to kill),but <STRING>TYPE:KILL seems to refer to the object to be hit.

Is there a KILL_CHANCE or other such variable I shouldbe using instead?

i just went and tested the kill effect, its %chance only works if its applied to a unit though its own monster file, but dw phan what your trying to do is relatively easy to achieve, ill show you how its done

1st.
make your procc skill(AKA the instant kill skill) here's an example, with details on the important settings

[SKILL]
   <STRING>NAME:Instant Kill Skill
   <STRING>ACTIVATION_TYPE:NORMAL
   <STRING>TARGET_ALIGNMENT:EVIL
   <STRING>TARGET_TYPE:TARGET (this is needed so the skill targets without a damage shape)
   <FLOAT>TURNRATEOVERRIDE:-1
   <INTEGER64>UNIQUE_GUID:-1630805785724599357
   [LEVEL1]
      <INTEGER>CHANCE:10 (this is your main man right here, the chance for the skill to procc)
      [EVENT_START]
         <BOOL>APPLYEFFECTS:1 (this will allow you to ignore putting on a damage shape)
         [EFFECTS]
            <STRING>TARGET:ENEMY                         
            [EFFECT] (your kill effect, no need to put a min/max just a duration)              
               <STRING>NAME:InstantKIllprocc
               <STRING>ACTIVATION:DYNAMIC
               <STRING>DURATION:INSTANT
               <STRING>TYPE:KILL
               <FLOAT>MIN:0
               <FLOAT>MAX:0
               <FLOAT>EXPLODE:0
               <FLOAT>NO_LOOT:0
            [/EFFECT]
         [/EFFECTS]
      [/EVENT_START]
   [/LEVEL1]
[/SKILL]

2nd
thats the procc part done, now for how to put it on your main skill, append this to any of your main skills level/s where the events are..

      [EVENT_UNITHIT] (event unit hit is used so you dont have to duplicate your damage shape)
         [EXECUTE_SKILL]
            <STRING>SKILL:Instant Kill Skill (your kill skill with the % chance)
         [/EXECUTE_SKILL]
      [/EVENT_UNITHIT]


<BOOL>CAN_CLONE:0
watch out for this, dont get rid of it if you want your skill to only procc on 1 target(picks a random target if you hit multiple units) other wise get rid of it if you want a % chance on each instance of each monster on each hit to procc your skill

that's it your done..
you can use this method for other things besides an instant kill chance and its procc rate can be controlled through levels so its a pretty handy set up to use if you have something in mind.

thanks gyt
if any of you guys are stuck on something skill related, ask me, ill probably know