Warframe now lets players lock one Riven stat while cycling, but doing so doubles the Kuva cost. Digital Extremes' Update 44 patch notes say choosing or removing the lock itself costs nothing.

Reapply the lock when you reopen the menu

At the Mod Segment, select the Riven's cycling option, choose Lock Trait and pick the stat you want to preserve. The lock remains until you remove it or close the Cycling menu, so select it again in a later session.

Locked cycling also preserves the number of positive and negative traits. A Riven with three positive traits and one negative keeps that arrangement while a trait is locked. Cycle without a lock if changing that layout is your aim.

The snowy Yuvan Peak hub in Warframe Update 44
Yuvan Peak is available with Update 44. Its Glacial Defiance missions are arriving later.Digital Extremes

Narin is available; Glacial Defiance is still pending

The September 23 update introduces Narin and the Yuvan Peak social hub. The six-player Glacial Defiance mode is delayed, with Digital Extremes listing a release on or before October 15 rather than an exact day.

Riven Splicing waits for that mode because the required Riven Splicer is earned there. Trait Locking is the system available now. Before spending Kuva, check both the selected stat and the doubled cycling cost.