One Thousand Cuts
The Tactical Alert One Thousand Cuts appeared in Hotfix 18.5.6. This was a series of new missions that appeared on Thursday and lasted until Monday.
Divine Will
The Divine Will Tactical Alert was a special mission on Venus that introduced the Razorback proxy.
Hallowed Nightmares
Hallowed Nightmares is a yearly Tactical Alert appearing around Halloween.
Project Undermine
Project Undermine was a Tactical Alert that saw the introduction of the Nightwatch Corps, as well as another run-in with the thief Maroo.
Emergency Exit
The Emergency Exit Tactical Alert was a special Alert mission where the Tenno protected two Bailiffs who were planning to defect from the Grineer.
Black Seed Scourge
The Black Seed Scourge Tactical Alert was a series of missions given to the Tenno by Frohd Bek, who was dealing with an offshoot of the Corpus known as the Black Seed.
Den of Kubrow
Den of Kubrow was a Tactical Alert in May of 2015, involving enhanced vampiric kubrow.
Blackout
The Blackout Tactical Alert was a series of missions given by Darvo from Friday, 10 April 2015, to the following Wednesday.
Ogma Elite
The Ogma Elite Tactical Alert was an Archwing mission available from 04 March 2015 to 09 March.
Phoenix Intercept
The Phoenix Intercept Tactical Alert was a series of missions that was available from 25 February 2015 to 03 March.