Riven Mods

Riven Mods are special mods that can feature up to four different stats, sometimes disadvantageous. Riven mods are unique in that their stats are heavily randomized, allowing for a significant variance in mod effectiveness, and because the type of Riven mod acquired is kept hidden from the player until they complete an assigned challenge for the mod. Riven mods are also exclusive to certain individual weapons, with each mod having only a single weapon associated with them.

A single Riven Mod is given to players upon completion of The War Within quest, and additional Riven Mods can be acquired as rewards from Sorties.

Upgrade and Trading costs of Riven mods are equivalent to those of Rare mods.

Challenges
When a player receives a Riven Mod, the nature of the mod itself is hidden from the player, a state referred to as being Veiled. In order to unlock the mod's type and effect, players must complete a challenge associated with that mod, for example, killing a certain number of enemies without being afflicted by Status Effects. In order for the challenge to be registered, the Riven mod must be equipped on a weapon that the player will be carrying into a mission. Riven mods that have not been unlocked will consume no mod capacity when equipped on a weapon, but will not confer any bonuses either.

If a player manages to complete the challenge, the Riven mod's type and stats will be revealed after completing the mission.

Stats
Unlike other mods, a Riven mod has randomized values for their various stats, i.e. two of the same Riven Mod can have different numbers for their effects. Each Riven mod has up to four stats associated with it: two or three beneficial effects, and possibly one counterbalancing negative effect similar in concept to Corrupted Mods. Both of these aspects mean that Riven mods are unpredictable, but at the same time their randomized positive effects have the potential to feature significantly higher values than standard mods. It is possible to receive a Riven mod that has high positive stats without any drawbacks, though the opposite is also possible.

Riven mods have unique, systematic names, consisting of a prefix, a core and suffix, following "Prefix-CoreSuffix" (as in Latron Deci-puratron). Prefixes and cores draw from the same name pool. There are 24 unique, randomisable stats and therefore 24 prefixes/cores and 24 suffixes. It should be noted that negative effects are not represented by the name.

The 24 positive stats are:

The prefix and suffix cannot be of the same stat, for example Dread Critacron or Tonkor Visiata is not possible

Cycling (Re-Rolling)
Another unique aspect of a Riven mod's stats is their ability to Cycle (re-roll) the mod stats and/or polarity, via the Cycle function in the Mods segment in the Orbiter by spending Kuva, a resource found through Kuva Siphon objectives in high level Grineer missions. Cycling a Riven mod will randomly reroll the mod's stats, which can result in either better or worse stats or effects for the mod, but will not change the weapon that the mod is assigned to first. Both the stats themselves and the percentages for the stats are changed when cycling a Riven mod. The minimum cost for Cycling a Riven mod is 900 Kuva for the first cycle, with increasing costs on subsequent cycles of the same mod.

Cycling (re-rolling) a Riven Mod will turn it back into its unidentified state, requiring the player to complete another challenge to unveil.

Putting ranks into a Riven mod and then re-rolling does not reset any ranks previously put into the mod (a rank 4 Riven mod that is re-rolled to a veiled mod will retain its rank 4 status even though it will not be view-able until the challenge is completed.)

Limitations
Unusually for mods, Riven mods are Mastery Rank locked, with different mods requiring players to be of a certain Mastery Rank to be able to use them. Also, each type of Riven Mod is exclusive to a particular individual weapon or its variation, and a weapon can only have one Riven mod equipped at any time. A player can only have up to 15 Riven Mods in their Mods section at a given time.

Trivia

 * Riven mods feature a dynamic image, which constantly shifts between the images of the bonuses. For example, a Riven Rifle mod that affects Critical chance and Critical damage (positively or negatively) will shift between Point Strike's image and Vital Sense's image.
 * Currently Riven Mods are limited to Rifle Primary weapons only (including some Sentinel weapons). This also extends to sniper rifles, bows, and launchers, as they are all considered part of the rifles group. Consequently, there are no Riven Mods for shotguns, pistols, melee weapons, Warframes, or Companions at this time.
 * To link a Riven Mod in the in-game chat, typing [Riven Mod] and selecting the mod you own will let other players see its bonuses.
 * Riven mods can be used on weapon variants, for example, a Sybaris Riven Mod can be used on both the standard and Dex Sybaris.
 * It appears that the stats are decided when the mod is still veiled (needs confirmation).

Links

 * Google Doc with possible stats in progress
 * Official Exhibit