The XV15 Stealthsuit is the smallest of all the various Tau Battlesuit variants, and is designed for use in operations requiring a high degree of stealth. Squads of Fire Warriors wearing XV15 Stealthsuits operate as the "lone wolves" of a Tau army, specialising in covert operations such as infiltration, sabotage, reconnaissance and ambush. The XV15 Stealthsuit is designed to be worn by a single member of the Fire Caste, and is the smallest of all the various Battlesuit variants of the Tau, as a Tau in an XV15 Stealthsuit is hardly larger than a Fire Warrior in standard Tau combat armour. However, this perfectly suits the XV15's role as the preferred Battlesuit of Tau infiltrators and saboteurs. XV15 Stealthsuits are significantly smaller than the XV8 Crisis Battlesuits, and, because of this, carry less weaponry. What Stealthsuits lack in firepower, however, they more than make up for with the ability to move almost unseen by the enemy until the very last instant. XV15 Stealthsuits are currently being phased out of mainstream use and being replaced by the XV25 Stealthsuit. This has led to their use becoming uncommon due to the XV25 now being the new standard Stealthsuit.
- Damocles Gulf Crusade - On the Tau world of Dal’yth Prime during the Damocles Gulf Crusade, XV15 Stealthsuit-clad Fire Warriors were used to protect forward Pathfinder spotter teams after Imperial assaults threatened them during their mission to pinpoint targets for long-range Seeker Missile strikes. Their Jetpacks and cloaking fields allowed the XV15s to respond quickly and effectively to the Imperial threats.
- Kappa Mortis Incident - The Kappa Mortis Incident was an important event that contributed to the future use of XV15 Stealthsuits. An Ultramarines strike force sent to the planet of Kappa Mortis managed to recover a single XV15 helmet from a crashed Aquila Lander bearing captured Tau technology. This forced the Tau Earth Caste to accelerate development of a new type of Stealthsuit as a result, rushing the single-weapon XV25 Stealthsuit into service ahead of the much more difficult to produce XV22 Stealthsuit they had hoped to introduce en masse. This caused XV15 Stealthsuits to become less common in Tau Hunter Cadres due to their replacement as the standard Stealthsuit by the newer XV25.
- Taros Campaign - During the Taros Campaign, the deployment of XV15 Stealthsuits proved to be an important component of the overall Tau strategy for victory. Stealthsuit teams would be inserted behind enemy lines where they would continually ambush Imperial supply lines, causing food and water shortages for Imperial forces on the frontline. This proved to be a major factor in the outcome of the conflict when the lack of critical water supplies in the harsh desert conditions caused an ultimate Imperial withdrawal from the world due to heavy losses from dehydration.
- WAAAGH! Skarkill - XV15 Stealthsuits were used as part of the first deployment of a specialist Stealthsuit formation known as the "Nighthunter Stealth Group," during the bitter fighting against WAAAGH! Skarkill. The Orks had captured an Imperial Mining World and were using the human colonists as slave workers to collect the planet's rich deposits of iron ore. This ore was used to begin the construction of a Stompa mob. The Tau found themselves hard-pressed to meet the Orks in open battle. Instead, Tau forces attacked the valuable mines, forcing the Greenskins onto the defensive. In doing so, the Tau gained the initiative in the conflict. In battle after battle, the Tau deployed their new Nighthunters. Each stealth group was inserted deep behind Ork lines or within the mine complexes themselves, using their stealth field generators to remain concealed. When the Hunter Cadres assaulted the Orks head-on in the mine complexes, the stealth groups opened fire on the Orks from the rear, negating the benefit of any cover they had taken amongst the overhead buildings. In all, the Nighthunter groups were deployed on 24 occasions. Though 8 of these groups were lost to Ork counter-attacks, WAAAGH! Skarkill was ultimately defeated thanks to their efforts. Warboss Skarkill's beloved Stompa mob was, thankfully for the Tau Empire, never built.
- Achilus Crusade - During the Achilus Crusade in the Jericho Reach, stealth teams of the Velk’han Sept were left behind on those worlds from which the Tau had willingly withdrawn. The stealth teams were used to confound Imperial forces that came to these worlds after the Tau withdrawal, and gather strategic data on the xenos' strength and tactics so the Tau Fire Caste could ascertain the strength of the human foe before committing their forces en masse.
XV15 Stealthsuits are worn by Fire Caste members who have attained the rank of Shas’Ui, normally after they have completed a tour of duty as the Shas’Ui of a squad of Fire Warriors. XV15 Stealthsuit squad leaders hold the rank of Shas’Vre. The whole squad is usually ritually bonded to one another according to the Tau custom of Ta’lissera, which is symbolised by a knife design painted onto the squad leader’s armour. XV15 Stealthsuit squads usually consist of 3 to 6 members.
XV15 Stealthsuit teams either operate in support of larger Tau formations, or range ahead independently from the main Tau army. They are not factored directly into Tau battle plans and enjoy a great deal of freedom of action and autonomy within very broad parameters that have been set down by Tau Commanders. This is because they are encouraged to fight independently and use their own initiative in assaults, as befits their combat style and tactical specialisation. The leaders of Stealth Teams are often regarded as being slightly eccentric by their fellow Tau and delight in employing new and unpredictable tactics because of this.
XV15 Stealthsuits operate in many different tactical roles, ranging from ambushing isolated enemy troops when they least expect it, to intervening in support of friendly units when needed. In the reconnaissance role, Stealthsuits can infiltrate deep behind enemy lines or move into forward positions unseen, where they can assault enemy units while they are off-guard and disrupt supply lines, like vengeful ghosts striking at will. The XV15 Stealthsuit enhances these roles as its integrated holographic disruption fields allow its wearer to sneak forward unobserved into advantageous firing positions before a battle commences. The suit's stealth capabilities make its wearers extremely hard to detect and the XV15's integrated Burst Cannon is the perfect weapon for ambushing lightly armoured troops and attacking the flanks of vehicles. The XV15's Jetpack also gives its wearer the manoeuvrability needed to redeploy quickly on the battlefield as the situation changes. Many a foe of the Tau Empire has found himself attacked from an unexpected quarter by Stealth Teams positioned far ahead of the main army.
When required, Tau Stealth Teams will be grouped together into formations known as "Nighthunter Stealth Groups," or as they are sometimes known, "Optimised Stealth Groups." These teams primarily consist of warriors wearing the newer XV25 Stealthsuits, and they will infiltrate far behind enemy lines long before the opening stages of a battle. Once the main Tau force engages the enemy, the Nighthunter Stealth Group reveals itself. It sets about sowing confusion behind the enemy's lines, destroying ammunition dumps, cutting off communications, and even engaging enemy troops too busy holding off the main force to notice the Stealth Group's approach. Caught between the Nighthunters and the main Tau army, the enemy is faced with a stark choice -- surrender or be cut down in the deadly crossfire.
The command and control teams of these formations, however, often opt to wear XV15 Stealthsuits instead of the now standard XV25 used by the Nighthunter line units. Whilst the XV15 is older and more lightly equipped, it has a smaller silhouette and superior signature shrouding, making it popular amongst experienced Tau warriors, especially when Nighthunter teams undertake close-in covert operations.
The XV15 Stealthsuit incorporates many of the standard features shared by most Tau Battlesuits. This includes a Tau Jetpack, which combines anti-gravitic and jet propulsion technology. The Jetpack allows the Battlesuit to maintain a stable platform from which to fire their weapons, even when on the move, and provides a great deal of mobility to the user. The Jetpack also allows for the Stealthsuit to be deployed from high altitudes by Tau transports such as Orcas and Mantas, where the Jetpack will be used to safely slow the Battlesuit's descent. In addition to the Jetpack, an XV15 Stealthsuit also incorporates advanced sensors common to all Tau Battlesuits that are built into the helmets. This allows for the user to gather more accurate battlefield data which can assist informed decision-making on where to best deploy the unit to maximise its tactical effectiveness.
The XV15 Stealthsuit also possesses the unique capability of camouflaging its wearer through the use of its stealth technologies. The suit's integrated holographic disruption field achieves its effects through a number of disruptor emitters arrayed all over the Battlesuit. This holographic disruption field can operate in two modes. The default, passive mode utilises a range of technologies to dampen the suit’s electromagnetic signature so that enemy scanners are far less likely to detect it. This mode is called "passive" because its use cannot be detected, as rather than attempting to interfere with enemy sensor systems, it simply masks the suit itself. In active mode, however, the suit's stealth field generator comes online. The suit's matte finish ripples and blurs, resolving itself into a nigh-perfect representation of the terrain that lies behind it, making the suit and its wearer all but transparent even to visual identification. In this way, the Stealthsuit's form is blended into the background as if its wearer was a Terran chameleon. In addition, when operating in active mode, the Stealthsuit's systems are actively interfering with and jamming enemy sensor devices. In so doing, the jamming itself will give away the fact that the Stealthsuit is present somewhere on the battlefield, but will make the detection of its actual location nearly impossible.
All XV15 Stealthsuits are armed with a Burst Cannon which is integrated into the suit's upper arm. This befits the Stealthsuit's role, as its wearer can lay down a hail of suppressive anti-infantry firepower using the weapon. The XV15 Stealthsuit can also use its Burst Cannon to target the usually more vulnerable side and rear armour plating of enemy vehicles. A stealth team squad leader such as a Shas’Vre can take a single item from the Battlesuit armoury, such as a Hard-Wired Multi Tracker, a Hard-Wired Target Lock, a Hard-Wired Blacksun Filter or a Hard-Wired Drone Controller to enhance his combat effectiveness. A Drone Controller allows for two Tau Drones, such as Gun Drones or Shield Drones, to accompany a Stealthsuit Team to lend additional firepower and protection. These Drones are equipped with the same stealth field generator technology that XV15 Stealthsuits use, which allows them to operate without compromising the Stealthsuit Team's ability to remain undetected. The Shas’Vre of the squad can also take a Marker Light to enhance the targetting capabilities of those Tau units the Stealthsuit Team is supporting.
- Apocalypse Reload, pg. 47
- Codex: Tau (3rd Edition), pp. 16, 25, 35, 60
- Codex: Tau Empire (4th Edition), pp. 27, 35
- Imperial Armour Volume Three - The Taros Campaign, pp. 78, 284
- Deathwatch: Core Rulebook (RPG), pp. 366-367
- Deathwatch: The Achilus Assault (RPG), pg. 16
- White Dwarf 321 (UK), "The Kappa Mortis Incident", pp. 76-81