After almost 1000 hours on this game and countless questions on this forum, I FINALLY made a build worth a damn! 
Core concept
Damage over time doesn’t stack from the same source, it just re-applies.
But from reading @grey-maybe’s 5 Guardian build and Mad-Lee’s Blade spirit build, it appears that each player-scaled pet (and each of their different attacks) counts as a different source.
So I thought:
“What if I had like… 15 of those pets ?”
This build is my answer.
Grimtools 1.1.9.6
GRIMTOOLS 1.1.9.4
GRIMTOOLS 1.1.9.0
Gear explanation
(Craft for +physique or slow resist)
- Blood knight set - Core to the build. Provides up to 4 bloodbathed pets. They have 2 different attacks, which should theoretically stack. for a total of 8 sources of bleeding damage. Also provides another more powerful pet with a wide bleed RR aura and a bleed attack (so 2 more sources)
- Scarab shell - BiS. An impressive increase to the damage potential of blade spirit. since they each have 2 different attacks, this bonus is applied 6x. Try to get one with Physical resist.
- Deathstalker relic - Another powerful pet that deals bleed damage and has a bleed debuff. Deathstalker also has 6 different attacks, which should all stack.
- Mythical Brutalax - Alternatives are Butcher of Burwitch, Misery and Bloodborer. Bloodborer prevents the use of Shadow strike, and Misery lacks any other meaningful bonus. Totally normal buckler is also a decent alternative.
- Mark of Plagius - Boosts Vire’s Might and has room for a prefix for Blade Spirit. Mark of Kalastor also work here if you don’t need help with Blade Spirit.
- Lacerator girdle - Provides a great source of AoE and DR
- Valguur’s touch - Morgoneth’s grip is also possible
- Rimestone legguards - +2 to Blade Spirit and a trail-mix of defensive bonuses. Reaper’s legguards are also a great choice here. If you don’t need the extra points for Blade spirit Grava’Thul’s legguards would provide more RR.
- Windshear greaves - Or well-rolled Stoneplates, if you need to fix weak spots.
- Menhirian - For raw stats. Used to be Prime ring of morgoneth, but lacerator girdle now pulls DR duty
- Cronley’s signet - Any green ring with the right affixes to boost Blade Spirit and fill gaps in our build works here. A Malmouth Blade seal also works.
Skills and devotions
Active
The build only has a few active skills and they are almost all for mobility and/or survival
Vire’s might is a good %WD source and a great mobility tool. Its best feature for our case here however is a single point in volcanic stride makes it one of the best devotion proccer in the game, as the flames hit multiple times per second. (as @MysteryMeat explains in his Skater build )
Perfect to bind Living shadow, and REALLY good at proccing our 2 “on attack” summons.
Shadow Strike gets Howl of Mogdrogen. This gives it a nice 68% chance to proc, but Nightfall hits multiple targets, making this more reliable.
Blade Barrier can be used as often as needed as it has virtually no impact on DPS.
The only other active skills are Wendigo Rush, Pneumatic burst, and Ascension.
Passive
Blade spirit is our most potent source of damage, and it gets rend since it hits more often than the other summons and Rend has no cooldown.
Guardians of Empyrion for the RR aura, and they are also great devotion proccers. So Bat goes there so we have some sustain even if stunned/frozen/etc.
Divine Mandate For the crit damage and slow resist. You could also go with Path of the 3 for some cooldown and vitality damage. Both work perfectly fine.
Gameplay
All we really need to do is avoid hits and keep our pets out.
We have a lot of different sources of sustain, many of which are completely passive.
Use the 3 mobility skills to zoom around and avoid hits, creating as many attacks as possible to proc our pets. Use Pneumatic burst, Ascension and Blade Barrier as needed.
… That’s pretty much it.
At rest the build has 7 pets out, but quickly goes to about 10-11 after one Vire’s Might use.
At full strength it has 17, 12 of which deal meaningful damage.
Performance
Crucible
Clearing crucible is quite easy to do, but clear times are never going to be particularly good since most of the damage output is passive.
The only timed run I did was 7:28
Could be improved, but probably not enough for that sweet [Cr+] tag.
Grim Dawn - "Pets" Bleed Dervish - Crucible - YouTube
Shattered realms
Screenshot proof for the build compendium:
SR 75 and up is starting to get a bit more challenging. Kaisan in particular is really problematic for some reason. A good pilot with decent mutators could probably take this to SR85 or more.
Celestials
Ravager of minds was a lot of kiting, but wasn’t actually that hard.
Mogdrogen
A bit harder as his AoE disrupts our skating skills, but overall not too hard.
I tried Callagadra once and got bodied in like 5 seconds… nope.
I held my ground against Crate for nearly 30 seconds and shaved about 1/3 of his health bar, then stuff started raining and I died immediately. Maybe it can be done with this build, but not by me.
Conclusion
I love skater builds, but they really depend on you being on point.
Here the pets do the heavy lifting and we skate mostly for Kiting and proccing, so it’s much more relaxed. Hopefully this description appeals to you as well.
Please don’t hesitate to post questions and/or criticism: I’m still learning and I’m sure there are lots of ways to improve.
And if you try it out, I’d love to know how it went.
Thanks for reading!
