I am coming back on and finally covering my ideas for T3 ^^
First off I thought about what 'nids have, and I thought something similar could work for DE.
It is still okay for discussion about the tier-placements of wracks and grotesques, and the talos too I guess. Wracks could be either T2 or T1, and grotesques preferably in the next tier. The Talos is the closest thing to a walker-equivalent but I can see it fitting T3 as well.
So, as to units which I thought about for this (most of these are probably obvious since I haven't featured them earlier)
First off the Ravager. T3-tank, predator, fire prism, etc. Triple the firepower of a raider, vehicle armour (in TT you actually can't destroy a ravager with bolters! Woo!). As far as upgrades go, the dissie-cannons would make it do tons of damage to heavy infantry, but it would lose most of its anti-tank. Depending on how good the dark lances are, the upgrade should be fairly cheap, and maybe, reversible? The cost could be payed each time and you would have to wait for the upgrade, but it could be interesting for the tank to change between triple-lances and triple-cannons.
Other upgrades could include the flickerfield for a small shield, but I don't think it needs much else. Nightshields could be very interesting if they are implemented a little like smoke grenades or the flare but I don't know how well it would go.
Relatively cheap but weak. The Fire Prisms are already pretty darn fragile, so I guess the Ravager has to be even more.
Next up, the Haemonculus. T3 subcommander. This is a little like how the 'nids have it. They technically even have two subcommanders in T3.
Supportive commander. Provides a health-regen boost around him. Starts off fairly tough, but slow compared to other DE-units (same lines as the wracks).
Haemonculi have always had a lot of interesting weapons and weird items, and there's plenty of thought to what weapons he should have. My suggestions are to make him a little more interesting at ranged combat while still not being a huge "gun-hero". When he comes out of the gate, without any upgrades, he would start with a stinger pistol and a simple CCW. The stinger pistol would be pretty deadly to light infantry, maybe again with the theme of damage over time.
For upgrades, first a simple melee-upgrade of a fleshgauntlet, or, alternatively, the scissorhand. They are both quite similar. DPS-increase, power melee?
A ranged upgrade as an alternative choice to the first could either be the hexrifle or liquifier gun, like the upgrades I gave for wracks.
Of other supportive upgrades, there are so many options. I don't know much of which ones would be considered the most "traditional ones", but the suggestions I have are the Crucible of Malediction and Animus Vitae.
The Crucible is quite similar to a wargear already present. It is supposed to be a psyker-hunter for a haemonculus, but it would work great as a AoE attack that prevents ability-usage for a small amount of time. The visual effect could simply be a sonic blast. The sound could be a simple copy of the banshee-shout.
The Animus Vitae I considered as a close-range fleshhook, but probably a little more damaging and little less disrupting. Could also include a self-heal for the haemonculus.
Then the incubi. T3 squad with 3 members to start with. Can upgrade with a klaivex for 4. Heavy Infantry.
And my wild suggestion here is inferno-melee damage. The Tzeentch-marines and IIRC Dark Reapers had this for range, and I could see the incubi as a unit to at least try to take on super-heavy squads on their own in melee instead.
Fairly good melee skill (75 to 80?) and a small but quick disruption special.
Fleet would probably be the only ability they need, like the seer council. Incubi are pretty tough, and their HP should be no less per model than the seer council does (rather more, since they deserve something for the best armour dark eldar have!).
Against any terminators without lightning claws, they should win. They should do fairly well against nobs with upgrades and buffs as well as against lightning claw terminators.
For super units, my suggestion is: None. Dark Eldar aren't about huge creatures and tanks lumbering about. The best option I see is a Tantalus but I would much prefer if they remain as an army that doesn't feature a huge skimmer but rather a horde of smaller ones.
Those are my full unit suggestions.
For commander call-in units, I would suggest an option for power-free Incubi for an archon and a scourge-drop as a standard.
Another idea is a bloodbride-call for a succubus-commander, but that would mean forgetting my idea of wych-vanguard transformation
