There are several talent builds you can evolve Dehaka into, but this guide is focusing on the easiest, and in my opinion best, talent setup for the community as a whole: the Essence Collection Sustain build.

Dehaka's trait is that he heals himself for approximately 2% of his life for every Essence he collects. Minions normally drop 2 essence, and enemy hero kills drop 10. With this build, minions still drop 2, but hero kills grant 25, and you get an additional 10 from regen globes. So as long as your team is killing the opposing team nearby, or you're fighting around a minion wave, you can consistently heal up to full health while taking an absurd amount of damage.

If you're with a healer you can trust, going for a more mitigation focused build with Enduring Swarm + Symbiosis is great, but I've only seen one QM since the PTR came out that had a healer in it. We'll see.

Level 1 - Tissue Regeneration

This very quickly gives you an extra 50 healing per second. If it were your typical Regeneration Master, this would take 20-30 minutes of globe collecting, but here you can get that done by level 10. Note that this doesn't require Dehaka gathering the cap of 50 essences 10 times, just 500 total essence.

Level 4 - Hero Stalker

Grants 25 Essence rather than 10. This equates to about a 50% heal per hero kill depending on your level. With this build, your goal is to stay in the thick of things as long as possible and just take damage so your backline doesn't. Since you aren't always teamfighting around minions, I prefer this talent to the minion based healing from One-Who-Collects.

Level 7 - Essence Devourer

With this talent you can can quickly stack back to full essences from zero, especially if you're at the enemy core. If you're getting chased and happen to pass a regen globe, it's a nice 20%+ heal by itself. Early game though, it is fantastic for getting your level 1 talent, tissue regeneration stacked up to full.

Level 10 - Adaptation

This is just ridiculous healing, so much so that it makes attacking Dehaka disheartening. When people are wailing into you and your health bar is healing up for the damage they do, it just makes them sad. As far as tips go, make sure not to waste it if you're going to die anyways (I included a few clips of getting outnumbered. Some I survived, some I didn't. Learn from them.) Try to get full value from it, by not burrowing or using hardened shield as you cast it. There was a good discussion of Isolation vs Adaptation on reddit. Isolation has its place, but it is an ult that is very easy to waste/get baited out. To have a universal build, choose the always good Adaptation. If you want to ruin a healer or caster's day and flip a teamfight, isolation is a good bet. You do you.

Level 13 - Swift Pursuit

Ok, we have our healing taken care of, now lets work on our engage, and escape, since enemies are starting to get powerful. Swift pursuit lets you keep up with Lunara and Valla, and almost keep up with Illidan. Sweeping Strikes is stupid. The Relentlessesque talent, Whirling Dirvish is also good, and has its place. Just because you can walk through them while casting Dark Swarm doesn't mean that Muradin lost the ability to hit you in the face with a hammer. Ferocious Stalker is fun in conjunction with Lurker Strain and an organized team that has good intuition. That's not everyone though.

Level 16 - Paralyzing Enzymes

Ok, you stayed alive in a teamfight, caught up to the person who was left over and hit them with your drag. Now what? Your damage sucks. This talent puts a slow on them so that your teammates can catch up and put the hurt on.

Level 20 - Hardened Shield

All good talents here, but almost all assassins have some incredible burst at level 20. You still want to be up front so this allows you to stay alive. The Adaptation upgrade provides absurd healing, but incentivizes taking damage, since you heal for more than you took, and going to ham against burst assassins can drop you if they get a stun off.

(I'll be updating and improving this guide as I figure out the formatting here more)

Work with a buddy, preferably someone like Kael'thas, The Butcher, or Kerrigan who has a stun and can do decent burst damage. You don't do much damage by yourself, but you can lock people down so friends can follow up with their stuns.

The best healing rotation is to use your trait at 50 essences, followed up immediately by Hardened Shield. Use Burrow if you get close to death or want to ensure you get topped off. After you come out of Burrow, use Adaptation.

If someone is very low and you aren't desperately needed elsewhere, go for the kill. It will help sustain you and your dark swarm can do enough damage to finish people off. In the video there are a few times you'll see where I should have switched targets to a low hp enemy.

Fight in or near minion waves if possible for extra souls and regen globes from Essence Devourer.

If you're trying to bodyblock someone, don't use Dark Swarm or they can pass through.