Warframe is all about getting more powerful, and few mods in the game can give you a boost in power quite like Riven Mods. Riven Mods are extremely rare unique mods for weapons that can provide some benefits, from increased fire rate to more damage or critical chance.
How To Get Riven Mods
The primary way to get Riven Mods is from Sorties. Sorties are a particular set of missions with modifiers you can run once a day. A Sortie is three different individual missions, each with a modifier. You will need to have completed The War Within story missions to have access to Sorties, and only Level 30 Warframes can take part in the missions.
You can hand in 10 Riven Slivers each week to Palladino, at Iron Wake on Earth, and in return, she will give you a Riven Mod.
Occasionally, you may be able to take part in a special Tactical Alert mission, generally as part of a special event. These will populate in the Alert bar in the Navigation screen, and will always offer some special reward. Sometimes, that reward will be a Riven Mod, although these are rare.
Similar to Tactical Alerts, Gift of the Lotus missions will populate as special events in the game, such as the game’s anniversary, and can often reward you with a Riven Mod upon completion. They will generally last for 24 hours, giving most people a chance to take part in them. These are great because they tend to be high tier rewards but straightforward missions.
Archgun Rivens are the only Rivens that you can regularly get in the game, as these are part of the Arbitration Honors, from Arbitration missions. In Arbitration missions, you will earn Vitus Essence, which can then be taken to the Arbiters of Hexis on any relay and exchanged for rewards. These include an Archgun Riven Mod for 35 Vitus Essence.
Almost by definition, Riven Mods are top tier items that are designed to be rare. They can get traded between players, and a vibrant Riven market, where people exchange Rivens for Platinum, can be found within the game. I don’t normally advise people to purchase Rivens, as the top tier ones tend to be dramatically overpriced, and not worth the Platinum that people are looking for. You are better off farming the daily Sortie and jump on chances to get extra Rivens as they arise in the game.
If you do want to buy a Riven, you are better off buying a bad one, then use the game’s mechanic that allows you to re-roll Rivens to roll it into a better version by using Kuva.