Well here is what I wrote about the Skyray in the vehicles guide. Hope it helps. I use a Skyray to boost my two Hamerheads BS.BS5 HH's are awesome and the Skyray has those eight nice Seekers.
The Skyray
The Skyray, a more misunderstood, under estimated and plain discriminated unit does not exist in 40K.
I am actually astounded at the level of ignorance surrounding the use and usefulness of this unit.
The main point that tends to get thrown into the mix is that the "Skyray" is not "”a tank”" OK and why is that a problem?. Lets get something straight from the get going, the Skyray is not and never has been a tank, it is an infantry fire support and marker light provision vehicle, just because it uses a heavy slot does not mean it is a tank.
So given the fact that it is not a tank we have to look at the Skyray in a totally different way to the way we view a tank. If you take a Skyray with the aim of destroying tanks or inflicting massive amounts of damage with the Skyray, then you really should not be taking a Skyray.
So what does it do then, well the Skyrays main function is as a mobile markerlight platform and this role should not be underestimated. To get the most out of this mobility and the markerlights it carries we need to equip it accordingly.
Best fit for the Skyray
Burst cannons for cheapness (you should aim to never use these)
Targeting array for BS4
Multi tracker to allow full 12" of movement and still fire the markerlights (absolutely vital)
Disruption pods to add to survivability.
The Multi tracker and Targeting array are the most important additions The Skyray has a maximum movement rate of 12" when added to the Markerlights range this means an effective 360 degree of table coverage out to 48". There are not many units that will be able to avoid being markerlit by a Skyray and this is the major advantage of the Skyray.
When your opponent realises how much of an area the Skyray can cover with its markers believe me it will make him/her think twice about where to move those valuable units, this can be used to good effect to effectively deny parts of the table.
When coupled to the Hammerheads massive gun range the mobility offered by the Skyray really comes into its own. Being able to cover most of the table with a markerlight enhanced railgun is a real advantage for the Tau player.
The other benefit is rapid response to changing tactical scenarios. The Skyray can get to most parts of the field quickly to provide marker support to a unit and this can make all the difference to for instance a FW unit in danger of being assaulted (24 shots at BS5 makes a bigger impact than the equivalent at BS3). Often other ML units will be out of range and unable to help, Skyrays do not suffer from this restriction.
Things like Basilisks that are concealed near the back of the field can be engaged by the Skyray The Skyrays seeker missiles have unlimited range and by deploying the SR 12" into the field then moving it 12". Allied with the 36" range of the ML you are looking at possible 1st turn kills on Bassies out to 60" (12” deployment + 12” movement + 36” range of the Markerlight).
It is very rare for all of the Basilisk to be totally in cover, so gaining line of sight to side or rear armour is usually possible.
The maneuverability is the beauty of the Skyray, its ability to make sure the opponent has very little chance of avoiding a ML on his valuable units cannot be underestimated.
Unfortunately one change wrought by the 5th edition rules has somewhat hurt the Skyray. In 4th edition the markerlights were totally immune to weapon destroyed results. Unfortunately this is no longer the case; markerlights are as vulnerable to weapon destroyed results as any other weapon. It cannot be denied that this is a real blow to the Skyray.
The only real weakness of the Skyray in 4th was it could be stunned or shaken and this meant its markerlights could not be used. In 5th however we have the added problem of the removal of the ML’s seriously reduces the usefulness of the Skyray. One way around this is to launce one of the Skyrays Seeker missile as soon as possible, with the intention of shifting the opponent’s attention away from the Skyrays markerlights and hopefully the opponent will elect to remove the seeker missiles instead of the ML’s.
The Skyray does make other markerlight toting units more viable, the fact is that you have a vehicle that can ML two separate units a turn, this means that the Skyray is brilliantly placed to provide ML support for two Hammerheads which leaves the other ML units more able to support other units like Fire Warriors.
If you take a unit of Pathfinders and a Skyray you can markelight 3 separate units a turn, with a Target lock in the Pathfinder squad you can ML four units a turn, to do this without the Skyray you need to either:
Take 2 Pathfinder squads, which is expensive and they lack mobility.
Take 3 Fire Warrior squads with markerlights or ML Drones and again this is expensive, lacks mobility and if the Drones are taken the cost goes through the roof.
Stealths with 2 Markerlight Drones. This choice used to be a real no-no but the new relentless rule in 5th makes this a real competitor to the Skyray. Mobile stealth field shielded Markelights allied to the Stealth’s fire power make for a really attractive and effective unit.
3 Sniper drone units, well Ok but the snipers ballistic skill suffers if the ML is used for other units and they have no mobility.
The Skyray has the advantage of being able to target two units a turn as standard. To do this with other units entails taking Target locks and usually upgrading one of the troops to enable the TL's to be equipped.
A Skyray is also a cost effective way of taking mobile Marker lights. A Skyray costs 155pts (optimal) and for this you get two mobile markerlights (able to fire at two separate targets) 6 Seeker missiles and two Burst cannons.
When we take into account the 60pts for seekers and 10 pts for the BC's this leaves 85pts, when we divide this by two the price of the markerlights equates to 42pts per markerlight.
Compare this cost per markerlight to:
Stealth squad with target lock with 2 markerlight drones and markerlight with target lock and BS filters for all others (for cheapness) works out at 275 pts. That equates to 47.5 pts per ML (taking away base stealth team cost of 180pts).
Fire Warrior squad with Shas'Ui (markerlight and a target lock) and 5 FW’s = 85pts, cheap enough until you realise you need two units to equal the Skyray and you get no mobility. So 170pts for two BS3 immobile markerlights compared to 155 for the Skyray (oh and you get 6 Burst cannon pulse shots with the Skyray, same as the FW squad)
The sniper squad is in my opinion not a valid markerlight unit because using the Snipers markerlights means a reduction in efficiency of the sniper drones.
So taking a Skyray is indeed a very cost effective way of providing extra markerlight support. Three units a turn can be markerlit by a Skyray and a pathfinder squad (4 units if a Shas'Ui is taken with a target lock)
Most of the above non Skyray squads have inherent drawbacks, Fire Warrior are expensive, have poor BS and limit mobility and can only mark one unit.
Sniper drones are Ok but if you use the ML to provide aid to another unit the snipers hit rate drops.
Pathfinders do suffer from lack of mobility but at least have lots of markerlights and ablative wounds plus a Devilfish that can now be used by other infantry units.
The Skyray is often seen as somehow depleting a list of firepower by virtue of filling a heavy slot that can be used by Hammerheads or XV88's. Well I do not agree with this, the Skyray has 6 STR8 missiles, how can that be seen as underpowered?
The Skyray is able to launch its own missiles at two separate units a turn and even if it is stunned/shaken its Seekers may still be launched in response to other units markerlight hits.
When you consider that many vehicles only get one main weapon shot a turn for 6 turns then 6 seekers should not be considered a bad deal when you add in the markerlight role as well.
The other thing to consider is that the Skyray is actually helping the remaining Hammerheads to perform at a higher level and the hit rate is actually nearly comparable to 3 Hammerheads at BS4. The hit rate equates to 1.66 hits a turn compared to 1.9 hits per turn for 3 BS4 Hammerheads, which equals 9.9 hits a game for the 2 BS5 Hammerheads and 11.9 for 3 BS4 Hammerheads’.
The three hammerheads do slightly better when using the solid shot but the improvement to the submunnition afforded by the reduction in scatter is also important. You then have to factor in the 6 seekers of the Skyray.
So really the loss of firepower is hardly a justification to not take the Skyray when you factor in its additional benefits.
Obviously the Skyray can be destroyed but then again so can that extra Hammerhead and it takes as much to destroy a Skyray as it does a Hammerhead. The Skyray can also help other units perform more efficiently with their markerlights.
In 1500pt or 2000pt games I firmly believe that a Skyray and Pathfinder squad make a very effective markerlight contingent and the Skyray enhances both the Pathfinders and Hammerheads in a list.
Obviously the potential for the loss of markerlights because of the rules changes in 5th does reduce the attractiveness of the Skyray it should still be considered a good choice if you require mobile markerlights.
With the advent of 5th edition the Skyray is no longer the only source of mobile markerlights in the Tau army. The new rules mean that any unit with a jetpack can now move and shoot with heavy weapons and this includes markerlights.