Tachyon Rifts are a type of mission.
Synopsis
The Avengers face new threats and take constant damage. At the same time, extra Heroic energy is given. These are timed events, and interacting with temporal anomalies throughout the area will extend that timer.
Higher power level is required for these missions, suggested at 140 or higher. Rifts rotate out daily and are repeatable. However, you will only be guaranteed the best gear once per day. After the first completion, you are guaranteed an epic or better gear piece. Rifts also have a small chance to drop exotic gear.
Each time you complete a Tachyon Rift with 100% completion rating, you will earn Cosmic gear, which has a chance to be special Storm gear, and Upgrade Modules. The first time each day you complete a Tachyon Rift, you will earn additional Upgrade Modules, a minor Artifact, and have an increases chance to obtain exotic Storm gear.