Councilor Vay Hek is done with your meddling Tenno. With the latest update in Warframe, The Grustrag Three will now hunt Tenno on a Warcframe account who messes with the Grineer.  Brief overview included in this article.

When will they hunt your Warframe account

The Grustrag Three is a new death mark enemy similar to Stalker and Harvester. For them to mark a Warframe account as a target, the player must complete at least five Invasion missions supporting the Corpus.  The player will then be contacted by Councilor Vay Hek regarding their meddling. They then have a chance to appear during Grineer missions. This is often signaled by a distorted message from Lotus regarding their presence.

Rewards for your Warframe account on victory

Defeat the three will allow you to continue the mission. Each of The Grustrag Three also has a chance to drop Neurodes, Brakk components, a rare mod or a rare Fusion Core. If you fail to defeat them, the Tenno on your Warframe account will have Grustrag Bolt attached to them lowering stats. You can remove this by building and using the Bolt Release item whose blueprint will be given to you. See you later Tenno!