First things first, Drukhari are an infantry-focused faction that hits its peak in the mid game and relies on mobility. Their early game is weak because you will be lacking the various buffs and synergies, and their units are baseline weak, especially the earlier units.
Also, their late game is also weak, because they lack really heavy combat focused vehicles and air units, or walkers. Their heaviest ground unit, Tantalus, is just a heavy assault transport like the Space Marine Land Raider. Not bad, but you won’t be playing tank warfare with the Drukhari, that’s for sure.
So, the goal for them should be to carefully scout in the early game, and attempt to gain the upper hand in the mid game by hitting at enemy weak spots and slowing their growth. If the game reaches Tiers 9-10 and you are still balanced with your opponent, you will be having a more difficult time once super heavies and other infantry-exterminators enter the game….
Economy wise their units are cheap, you shouldn’t struggle much BUT Drukhari are really influence starved. They definitely need a lot of influence, and you should store as much as you can in order to boost the loyalty of your cities (mechanics are still unclear to me but i noticed that it is not production that influences loyalty but total amount of influence, similar to Ork WAAAAAGH).
Of course Drukhari gain influence with each kill too, but you still need to make influence producers and not neglect them. Drukhari rely a lot on influence to use important abilities for both their units and faction-wide abilities too.
In terms of units, there are two styles of play and until you reach the end tiers, you need to focus on one: Transport-based warfare and Combat Drug-based warfare… While you can develop both at the same time, it will slow you down, so it is more optimal to focus on one at early stages of the game.
The Transport based group are infantry units that can’t use Combat Drugs by default (there is a T10 research to allow all infantry to use them). Such units tend to be squishy on their own, and have less mobility. Since the Drukhari have 3 assault transports, beginning with Venom, their basic vehicle, and ending with Tantalus, their heaviest unit, infantry that lacks combat drugs is better suited as an auxiliary carried unit rather than autonomous infantry.
You place the transport next to the target, unload the cargo, hit and kill, and then board the transport again in the next turn. Rinse and repeat. There is research to give significant buffs for 1 turn after exiting transports, that suit this playstyle.
Kabalite Warriors and Trueborne(this is a direct replacement of Warriors) should be used to kill organic units, Scourges for anti-vehicle and anti-building duties, and Incubi as your end game melee infantry that can deal damage to both armored and unarmored targets. You should also use the Archon hero with that group. Archon is a relatively well balanced combat support hero with nice weapons and the ability to soak overwatch easily.
The other group of units are those that can use combat drugs by default, the junkies, LOL. They tend to be more mobile even without the drugs, and can be deceptively tanky and deal decent damage too. Combat drugs are an ability that costs 20 influence for 10 turns, therefore it essentially adds an upkeep of 2 influence per unit for as long as you use them.
The drugs initially give just a +33% number of attacks, but there are 4 other buffs to research with the latest at T6 (17% morale loss resistance, 33% feel no pain damage resistance, +50% melee damage, move through cover). Those buffs can really transform infantry units (and heroes). Especially melee ones. The first unit at T1 to unlock for drugs are the Wyches.
They are a somewhat squishy but fast and very hard hitting melee unit. Later you should upgrade to the Hellions, who should be your primary combat drug infantry until you reach T10 and can switch to Incubii with combat drugs and Tantalus transports. Hellions are great vs organic units and very mobile, they are also very cheap.
For anti-vehicle you should rely on Reavers and Ravagers, which you should spam alongside Wyches and Hellions, until you finally replace them with the Tantalus later. Don’t make the weaker transports since Wyches and Hellions are very mobile. The hero to use with this group is the Succubus. She is GREAT. She is basically the Drukhari alternative to the Ork Warboss. Initially she seems squishy, but don’t let her full you, she can be a beast!
She can deal insane amounts of melee damage when fully buffed, and can be suprisingly hard to kill if you stack her no feel pain buffs and give her defensive items. She is also mobile as well. Make sure you give her Dusk Blade in order to life steal. And watch her slaughter everyone. She also buffs other melee infantry up to +50% damage…. For the money, she is crazy aggressive.
I left some units out that are more generic and should be used for both routes. The Haemonculus hero is very important for buffs and heals. And his offensive ability can deal great damage to armor, especially heavy infantry like terminators…
That hero can also heal for free every turn the “builder” (doesn’t build anything, just clears tiles) unit, Wracks, with an additional ability. Wracks is a tanky infantry that can hold your line, assuming you want to hold a line with Drukhari, and can deal decent melee damage to infantry even in cover, and can also deal nice damage to monsters.
They are very slow though. Still, you should have 1-2 Wracks per each Haemonculus hero at least. There is also the Cronus monster unit, which is also important to have at least 1-2 at all times. Each time they have attacked in a turn, they gain a 6hp heal, and they also double the feel no pain bonus units gain at lvl 3 when next to it. It deals decent damage to infantry in cover as well.
When you combine Haemonculus, Cronus, and the other buffs units get, infantry becomes really impressive for the price. Just try to place them tactically next to each other to stack the buffs, since most auras are range 1.
As for the air units, they are decent. Nothing impressive but they get the job done, the first air unit is nice vs air and decent vs ground, and the bomber is better vs ground. Standar Gladius fare.
Soul Hunger abilities, the ones you can press at the up-left corner of the screen, should generally be spammed on cooldown. They ARE expensive but they are definitely worth it for all the buffs and income. That is why as i said you should definitely have lots of influence production.
Make sure you make enough influence per turn to pay for their upkeep. The ability to create a temporary Webway Gate is really cool, it allows you to either return to your base if you are far, or attack anywhere you want on the map if you are next to a Gateway. Can be very effective.