I recently posted my Dr. Death acid retal support combat medic, and got very excited about another premise for a Combat Medic build. 
This is that build!
https://www.grimtools.com/calc/vNQLrDEZ
**Edit: Click here for Cruci Video
:: Edit ::
https://www.youtube.com/watch?v=rwv0ty4BdPs
Here’s a video of soloing 160-170 in Gladiator Crucible. It’s slow, but safe, and you can see that the only serious threat I encounter is tanking 2x Aleksanders at once, but even that proves to be fine. I’ve got 3 lightning towers; two are 2nd tier, one is 1st tier. I believe that this build can get to 150 Glad crucible with no banners or crucible buffs, but it was late and I wanted to speed things up. I’m not yet sure how it would go in 150+ crucible without buffs/banners. It may be possible, but I think it would be hard from 160+ ! 
:: End of Edit ::
It DOES have a green MI, but of one run through to Kilrian, and one through Steps of Torment got me two strong candidates for shields. I’ll keep an eye out for a double-ret shield, but for now this one seems to do.
I love the THEME of this build. It uses Drain Essence to soak up the life force of the enemy, before dispersing it as healing across your team. I love that the drain essence magic colour looks similar to the Apothecary’s Touch colour, which let’s one fall into this theme!
The Necromancer Healer, that is this build! It is a PHYSICAL RETALIATION damage caster support, with a few strong heals: Healing Rain, Empyrion’s Touch (Auger set heal), Apothecary’s Touch.
It also grants nearby team members +4% attack damage converted to health, and provides decent damage mitigation with Stone Form.
For added support, the build has a nice 20/12 Field Command and 17/12 Squad Tactics for damage, attack/cast speed boosts, +29% armor and +142 OA and DA.
To assist with damage mitigation, War Cry and Ill Omen can be staggered to ensure a 100% uptime on 25% damage reduction to all nearby enemies.
This build has not bad damage on the Drain Essence, critting for 50-60k damage in campaign to multiple enemies (or just 20-30k noncrit). This build has a low OA, so critting bosses isn’t the most common, but the damage output for a SUPPORT BUILD is quite good! The cast speed allows for ~5 ticks per second, so it’s not the worst damage per second, but certainly not the greatest.
Damage is assisted of course with the retaliation damage on the build, adding other heavy hits of 100-180 retaliation damage to enemies to get close enough to attack.
The build slaughters masses of trash really quickly, it’s incredibly fulfilling to soak up the life force of entire groups of enemies. It’s like a Grim Kirby from Smash Bros.
To assist with damage mitigation for the Combat Medic, we have Overguard for flat damage absorption and Mark of Torment for short stints of % damage absorption. These can be staggered, and with Stone Form proc’ing, it’s rare to find yourself taking spike damage, even with lowish phys resist. Having a decent armor rating of up to 3800 is helpful.
The damage mitigation, combined with nearly 4k HP regen with all buffs active, plus 35% attack damage converted to health on a 9m wide Drain Essence ticking 5 times per second and decent stun/freeze resist makes this build more or less immortal.
I am yet to test it versus celestials, but look forward to doing just that.
I’ll keep you updated on a fight with Callagadra. This build has very low phys resist for tanking Cally, but incredibly good healing and other forms of damage mitigation. I’m looking forward to seeing if the build is effective or not!
It’s worth mentioning - even if this build does not critically hit often, it only needs to crit once for Assassin’s Mark to stay on a target for 18 seconds. If you’re hitting ~5 times per second uninterrupted, that means you’re hitting the target for 90 ticks within that. If any one of those is a crit, then Assassin’s Mark procs again, keeping the uptime of it fairly constant.
This build is not the best dedicated support, or retal build, or damage dealing caster, but it is a beautiful combination of all three that makes for very relaxed gameplay, and provides significant assistance to your team.
Enjoy!