DISCLAIMER: I know Aun'va & Ethereals have been battered in other topics. This is a mere response to a request...read only if it might please you (personally I found writing it to be painful so Lord alone knows what it's like to read

)...
Let’s say you are given a challenge. That challenge is to win using Aun’va as your 2nd
HQ choice in a 1,500pts Tau army. If you manage it you win some cake*, the best cake in the world in fact. How would you use Aun’va to secure your cake of immense winning victory?
Aun’va – 205pts
WS1 BS3 S2 T3(5) W4 I1 A1 LD10
Sv 4++
Paradox of Duality (
CCW)
Supremely Inspiring Presence – All Tau within
LOS are Stubborn (Ignore negative
LD modifiers).
Stubborn may only come into effect against certain kinds of shooting attacks – or else in combat. If any of your Tau units get into combat the chances are they will struggle and most likely die. However if by some miracle they DO survive this may potentially give you a contested objective by the end of the game. It may also give you time to get some Kroot into the fight to help out – if you’re Tau are not already wiped out.
The Ultimate Price of Failure (see: FAIL) – Should he die every Tau unit must make a Morale Check (typically LD7-8) unless in combat or already falling back. If they take the test (even if they fail
IMO) then they gain Furious Charge & Preferred Enemy for the remainder of the game.
On any other units in the game this would be awesome, but for Tau it simply makes them normal. Crisis Suits may gain some extra
raw punch, granted, but the majority of enemy units contain some Power Weapons/Fists or Rending or Poisoned weapons of some kind and will likely still strike first or simultaneously. The Paradox also increases the unit’s Toughness to 3(5), but also provides a 4++ Cover Save that can be re-rolled. This is in itself not bad, until you realise all you need to do is score 3 wounds with a Strength 6 weapon in order to Instant Kill them all. Given this Aun’va is perhaps best used as a screening unit for Sniper Drone Team Controllers or…erm…yeah, those you’d probably put into Cover anyway
Aun’va is accompanied by 2 Guards:
WS4 BS4 S3(5) T3(5) W2 I3 A3 LD10 Sv4++
Honour Blade (+2 Strength as above) & Counter Attack
The Guards may be able to kill a few Infantry in combat, if they survive given their low Initiative. They have no armour save and only their T3(5) & W2 for protection. They will most likely be outnumbered as well & enemy units will still get an armour save.
Aun’va
IS a paradox in duality – in that he is probably at his most useful when he dies & even when he does you still won’t want to assault with your Tau units unless you have to, given that they are a ranged/shooting army and will not be on par with most Infantry units in the game even with the skill buffs.
On the plus side he’s only 205pts
I won’t go into Ethereals too much. They are lesser versions of Aun’va for 50pts each, can take an Honour Guard Squad of Fire Warriors for +2pts each, giving them +1BS in the process, as well as making them Fearless. If they get caught in combat, they die. The Ethereal allows re-rolls to Morale & if (when) they die, they’ll have the same effect as Aun’va withut the Furious Charge ability. They may save a unit or two from fleeing after shooting wounds, but in combat the re-roll is next to useless. Their Honour Guard may be better at shooting than your normal Fire Warriors but at 170pts minimum for the unit I fail to see the benefit.
I could be wrong – if anyone who plays Tau uses Ethereals (or Aun’va) with success – please contradict everything I’ve just written. Even my optimistic rule dementia can’t see anything that redeeming in either – unless you build an entire list around them using somekind of unconventional, jedi mind-trick of a tactic.
Ethereals are, for me, the trickiest unit in the Tau army to make useful, from a design perspective. They are meant to be inspiring Leaders, little more. They have no psychic powers or abilities to speak of, they aren’t combat monsters, nor uber-ranged units. They are not the Generals of the Tau, so that rules out any benefits to ‘Seize the Initiative’ or deployment/moving units etc...
If Ethereals had a rule similar to Calgar’s ‘God of War’ this would be better than a standard re-roll. If they would give certain units within x’’/
LOS – Counter Attack, Preferred Enemy or Feel No Pain (basically if they could give a unit a skill buff per turn) then they’d have some use. This could be justified from a fluff perspective for the Ethereals direct the destiny of the Tau and have some effect upon their minds – it would fit a ‘mind over matter’ Philosophy which seems to exemplify the Tau race with their technology belying their physical capabilities.
It will be interesting to see what
GW does with the Ethereals (I don’t want to get into the rumours here - although I've read they've killed Aun'va - if so GOOD) but for now, if I was playing Tau, it would be Crisis Commanders every time.
*The Cake is a Lie!