XV104 Riptide Battlesuit
The XV-104 Riptide is what would happen if the Tau found a old DVD of Gundam and got a hard-on. A battlesuit "equivalent" (read: inferior) to the Imperial Knight, it was the Tau's largest Battlesuit outside of Forge World until the Stormsurge was released (some don't consider it to be a battlesuit because it lacks the keyword) . Resembling the lovechild of a XV-8 Crisis Battlesuit and the ZZ Gundam (from the Mobile Suit Gundam series of the same name), this mecha was once pure awesome! While it was nerfed hard in the initial Indexes of 8e, the Codex is set to help it make a comeback.
Fluff
The XV104 Riptide was first introduced during the Third Sphere Expansion of the Tau Empire. When the Tau needed to break the siege at a pair of Hive Cities that the Tau were having trouble with. When everyone's favourite waifu Shadowsun was told of the failure to breakthrough, she decided to break out her new toys. This was the introduction of the ZZ Gund... sorry, the XV104 Riptide Battlesuit. Striding onto the battlefield undeterred by the shitload of dakka that was coming their way, the new battlesuits basically ripped the Imperial defenders a new one. When the Imperial troops sent guided missiles Deathstrike Missiles their way, the riptides were unscathed, protected by their Riptide Shield Generators. They approached the Imperial defences and blasted holes in them with their High Mega Canno... sorry, Ion Accelerators.
And so, like THREE of these things effectively conquered an entire Hive World.
The Riptide soon spread through the Tau Empire, being the lure for thoudsands of preteen GW customers with too much money and not enough playtime. It soon reigned supreme over the fluff battlefield and the meta one. The reason given for its ludicrous $130 Australian Dollars price tag is that the Riptide's extremely tough and "impenetrable" armor is made from a super-rare material called Fio'tak Gundanium. The real-life reason for the cost is that GeeDubs are just screwing with you to get your money. They use a super-powerful engine called the Nova Reactor to overdrive their capabilities to the max, allowing them several things on the tabletop, most notable the ability to overpower their two weapons.
On the Tabletop
As of 8th Edition GeeDubs decided that they couldn't have the Riptide spam of 7e. So, as with all good things, it came to a end when they decided to make the Riptide take a Mortal Wound every time it uses it's Nova Reactor. Back in 7e they had a 1/3 chance to take a wound every time a Riptide used its Nova Reactor, but in 8e the damage is assured. The only way to avoid it is taking the Stimulant Injector upgrade, which gives Feel No Pain. This allows you a 1/6 chance to avoid losing damage, which is substantially less than what it was in 7e, and also costs a few extra points, which would be otherwise better spent on another of what should be two upgrade hardpoints.
In addition, the Heavy Burst Cannon is weak as hell. It gives a increase of one strength from the standard Burst Cannon found on XV-8 Crisis Battlesuits and more shots. The Ion Accelerator (which is arguably the better weapons choice) costs 104 points on top of the already expensive unit. This means that you'll mainly be using your huge-ass suit in a anti-infantry role, and not actually blowing holes in enemy Imperial Knights. In fact, this relegation to a inferior and already-redundant role means you'd be better off spending the absurd amount of money on a unit like the Hammerhead Gunship, which can put some dents in a enemy Titan for a cheaper price.
It is also rumoured to be greatly reducing the points cost of both the suit and its weapon options. So don't leave them on the shelves just yet. #
*UPDATE* As of now, post Codex and Chapter Approved 2018 the Riptide has all but returned completely to its former glory. For starters it went down to 185 points base. The Heavy Burst cannon chews through GEQs and MEQs like they were tissue paper for only 35 points, thanks to both its healthy 12 shots base and 2 damage per shot. All for a decrease of 20 points! Hell with Nova Charging and/or the Command and Control Node Stratagem (Reroll wounds) you can rip through vehicles with the sheer number of shots fired. Meanwhile the Ion accelerator has been tweaked too, what used to be its overcharge profile is now its base while the former nova charge is now the overcharge. And it dropped a whopping 54 points! There's been a change to the nova reactor on top of these. Nova Charging ramps up the Heavy Burst Cannon to 18 shots and gives the Ion Accelerator the maximum number of shots instead of another redundant stat profile. Overall you'll be set back between 262-283 points (Assuming the pretty much mandatory target lock and the fact that you have no reason to ever put Plasma Rifles on it) base for a single Riptide as compared to the Index's 316-362, making them far more spammable than they were at launch. It's perfectly reasonable and even fairly competitive to field 2 of them. Did we mention there is also a stratagem that grants you 2 Nova Reactor effects for only 1 CP? 3+++ Invulnerable and boosted weapons? Yes please! Overall, the Riptide has returned to its proper place in the Tau army. So feel free to dust them off and enjoy the hatred they bring your way once again.