Exclusive to Fire Warriors. So it came upon the Hamster to improve this rather terrible selection and so he made an attempt: It's cheap and could give you back what you once thought lost. Having an S7 rapid fire gun that can shoot up to 48" is nice to have, along with two S6 melee attacks up close and two wounds.
Only one of each can be taken per army. These are almost necessary for a good army although they do cost 80 fucking points!. Take Fire warriors instead, especially since these guys have no Supporting Fire.
Dread Pirate R'myr, who inherited the name from four previous commanders, is a decent suit that seems to want to be charged. Hordes of light vehicles? Unless you have other plans or points are too tight, you cannot go wrong attaching a pair of these to Crisis suits, as they are tough enough to weather some anti-infantry fire, but not so robust that they can easily survive anti-armor weapons.
The rest will be discussed in their related entry, like the now Broadside-exclusive MV8 Missile drone. You may win battles, but that is not your goal as a Tau player: It lets you ignore Night Fighting and Blind effects.
If you put this on your Commander you'll miss out on his sweet BS5, but at least it will be on your longer lasting model.
Take 3 in a squad, give them all 2 fusion blasters pts. Let us reiterate what her Command-link drone does: Useful as a last 1 fingered salute to anyone assaulting you and not much more.
Devilfish give Fire Warriors much needed mobility, and safety from assault. And she can do this every turn. Just be prepared for the assault, cause their weapons are so short ranged that his consolidation move will not get you out of charge range. Note that if you're running a Farsight army, this is mandatory.
After all, isn't passing Look Out Sir! Those casualties will slowly add up, just like your unit's price tag. This is especially hilarious when combined with 30 man Kroot squads stretched out from table edge to table edge, allowing for units 30 inches from the assaulting squad to auto-hit with flamers.
You know how that Riptide's Nova-charged Heavy burst cannon is almost as dangerous to itself as the enemy? But it's quite cheap and perfect for small squads: Allows the model to fire at a lunatic psyker a slot target from the rest of the unit. Perfect for Tetras and Sky Rays, if close to your units.
They have 3 hardpoints which they can fill with any combination of weapons or systems you want, but filling all 3 isn't mandatory. It can be useful for opening tin cans or crumpling lower key characters in challenges.
Gives Move through Cover. Combine it with Coordinated Firepower to get BS5 even before using markerlights.
Consider equipping them with this plus a burst cannon and a cyclonic ion blaster to maximize the odds of sniping special weapons and characters from enemy units as a kind of tactical-level Mont'ka maneuver. The real selling point of Ethereals however is precisely that - their selling point.