The most important thing to know about Kheldians is that there is a custom enemy type the devs added to the game just for them. The three major varieties are Quantums, Voids, and crystals.
They are pretty much guaranteed to be in any mission that has a kheldian in the party and are also found randomly dispersed throughout most zones.
If you've ever teamed with a Kheldian, you have seen them call out "Void" or "Quantum" (or V & Q for short) every time there's one of these types of enemies in a group. This is because in most cases, a kheldian can only take about two hits from one of these before dying so they want the team to know to focus on that one first. Killing them before they kill you is a challenge and something that you become very good at very fast… or else.
Quantums
This can be any enemy type and look normal until you get close. Then they pull out that massive glowing gun that will make you scream like Michael Jackson and head for the hills (or hospital). They are challenging in that they look like any other enemy and you'll only know they're there by checking groups before striking or by attacking and watching them pull out the gun-of-kheldian-doom.
A neat trick for dealing with Quantums to close to melee range quickly. They'll often punch you instead which doesn't hurt any more than any other enemy of that type.
Voids
Typically these guys are black all over with a red face mask. They're very easy to spot because they look nothing like the group of enemies they're with. They also occasionally make a "whoooozaa" kind of noise making it pretty clear they're nearby even if you don't see them.
Note that the "whoooozaa" noise I'm referring to is an anit-kheldian shield that makes it much harder to kill them. If you're soloing or fighting a high level void, wait until the glowing aura around them subsides to start your attack.
These guys are far more dangerous because their punches are as powerful as the ranged attack and you won't last long if you have their attention. The only thing to do with Voids is to avoid them (no pun intended), let other's draw their aggro, or hit them with everything you've got so fast that they can't retaliate.
The all-out attack method can work well, but at the lower levels when you don't have a lot of attacks, this will get you killed more often than not. Let's just say that it's nice that the devs added debt protection below level 10 and you have that nice travel power to get back to the mission that you were killed in over and over.
Shadow Cyst Crystals
Out of the three, this is by far the most dangerous. There are certain missions in the game that have "portals" that continuously spawn enemies until you destroy the portal. This is normally not a problem because they can usually be avoided (which keeps them from activating), spawn a small number of enemies at a time, spawn only lower difficulty enemies, or spawn only minions (ex: ritki portals and cot portals assuming you're not on a giant team).
Here's where the crystal becomes a problem:
Oh, and one more thing, you don't get any experience from the nictus it spawns, just the crystal. Peachy, huh?
So unlike the classic anti-kheldian stuff, crystals can quickly become a problem for the whole team. Fortunately, they're a lot more rare, but unfortunately, you never know where or when they'll pop up and, when they do, it's almost always by a critical group of enemies you have to take out (so avoiding them just won't happen).
 |  | I've found that crystals only pop out on teams of 7 or more. Keep that in mind when forming TFs and such when a Kheldian is on the team. |
One crystal can ruin an entire TF
Like most portals (only more so), the best way to deal with them is to have everyone in the group hit the crystal at the same time and beat on it until it's gone. All this while getting pummeled both by the group that the crystal was in and the nictuses it spawned. Chances are that some or all of you will die, but if you don't get rid of the crystal immediately, you have no chance of finishing the mission.
Here's a bind that can save you a lot of grief. It will target anything with the words "Quantum", "Void" or "Crystal" in the name. When you push it, it will immediately target this type of enemy even if you can't see them very well due to caves, poor lighting, or tightly packed enemies.
/bind v "target_name quantum$$target_name void $$target_name crystal "
Use this every time you line up for an attack and you'll very rarely be caught unprepared (the most common reason kheldians die).
Use this one to alert your team once you have the offender targeted (explained in more detail in the macro section):
/bind f8 "local Ick! It's a $target"
