When the War Within came out, it introduced Riven Mods, often just called rivens. The idea was that you’d receive a veiled mod with a challenge on it. Equipping this mod on a weapon and completing the challenge would unveil the riven and produce a mod for a specific weapon with randomized stats on it. These mods would cost about the same as rare/gold mods to upgrade and would ideally be a huge buff to unpopular or bad weapons, since the randomized stats included would give you more space for other mods, allow you to experiment more and try out new weapons.
It does work, kinda. I received a riven for the Harpak, a Grineer burst assault rifle, which gives me +288% more damage, on top of my Serration base damage mod and my status mods. I got the normally not very good Harpak, tried it and ended up quite liking the weapon. I now take it occasionally to sorties.
While it all sounds nice and fun, everyone quickly realised that 1. the majority of weapons still aren’t that good even with corresponding rivens, 2. there’s so many weapons that it’s unlikely you’ll get the weapon you want, 3. everyone only really wants rivens for weapons they like, creating a market flooded with shitty rivens for shitty weapons and 4. 99% of the time your randomized stats will be horrible.
The problem of everyone wanting rivens for their good weapons was always going to be a thing. The developers have tried to deal with this using disposition. The stronger the weapon, the lower the stats. Because my aforementioned Harpak is an unpopular riven, it can reach much higher numbers for its stats, almost hitting 300% damage. A riven with the same stats for a Soma or a Tigris, two incredibly popular weapons, would most likely have lower numbers.
Luckily, with number 4, that problem can be solved with the ability to ‘reroll’ mods. You can do this by spending Kuva, a resource only found on planets which the Kuva Fortress passes by, to get a new set of randomized stats. You can either keep your old stats or choose the new stats, which ever riven you prefer. The name of your riven is also randomized and somewhat unique and changes whenever you reroll your riven and take the new one.
Except rerolling rivens comes with its own downside. Kuva is one of the most tedious things to farm, ever, and it only comes in batches of 500-600 and 1000-1200. Not great when rerolling a riven costs more each time, starting from 900 kuva and maxing out at 3500 kuva.
A Kuva Siphon mission (or its level 100 counterparts, Kuva Floods) replaces a normal mission – while the normal objective is there, there’s also a secondary objective of stopping the Grineer from gathering kuva. They require you to use your space kid to jump though clouds of Kuva before they enter the Grineer Queens’ siphon. Defending it are a bunch of high level Grineer, including the fat bastard immortal enemies known as Kuva Guardians that you have to fight in the War Within. It’s chaotic at first, but it quickly becomes boring and tedious, especially when you have to run around and find the damn siphon in the first place. Worse, there is a lot of downtime between Kuva clouds and the reward isn’t always a round number. Many a time, you will complete a siphon and only get 590-ish kuva, when you needed 600.
Even worse, you can’t repeat Kuva Siphon missions. Once you do them once or twice, the mission node returns to normal and you have to do another mission. Generally fast missions like Capture and Exterminate are the best for Kuva Siphons, but often you’ll find yourself wading through a Mobile Defense or a Survival mission, just for a handful of kuva. You find yourself needing to do 3 Kuva Flood to reroll an already heavily rerolled weapon. Yes, you can now get 6000 Kuva from sorties, or 1000 Kuva from the higher tier bounties on the Plains of Eidolon, but instead you could have gotten a Riven mod or one of the actual new items available as a bounty reward.
Oh, and you’ll probably reroll your riven into something else completely mediocre. You’ll probably get sick of the space kid as well.
But this is all assuming you even GET a riven mod or three. The only way to get them is a 20% (approximately) chance of receiving one after completing a sortie. It’ll either be a shotgun riven (for shotguns that go in the primary slot), a secondary riven, a melee riven or a rifle riven (any non-shotgun primary). So the chance of even getting a riven for a weapon you like is incredibly small. And you can go for weeks without getting a riven. Melee rivens were introduced with Chains of Harrow, yet I got my first melee riven on August 31st. It was for the Dual Razas, a very, very mediocre weapon. Just like all my other mediocre rivens.
The worst thing though is that there’s a limit of 15 rivens per account, and you need to purchase more slots, up to a maximum of 90, with platinum only. Reach your limit and you can’t do sorties until you delete some rivens. For people who do sorties daily, which is the majority of older players, you’re probably going to hit this limit at some point.
And most likely, all you’ll have is a bunch of rivens for weapons you don’t like that need a huge amount of kuva to reroll. Which is exactly what’s happened to me. I have 8 rivens, they’re all awful apart from two of them, my Sonicor riven and my Harpak riven.
Oh and my new, overly rerolled IGNIS RIVEN.
Which still has shit stats. Even after 17 rerolls at 3500 Kuva a go.