From Destinypedia, the Destiny wiki
High-Value Targets, or HVTs, are special enemies that can appear in Patrol or during Gambit matches.
About halfway through the game, a High-Value Target will appear. It will be a glowing Major enemy of the same race as the one currently being fought. It will spawn at a Front, and move through them all the way to the opposite side. If not killed in time, it will disappear. When damaged, it will begin leaking Motes of Dark, and will release a shower of them when killed, alongside a Heavy Ammo Brick. A total of 12 motes can be collected from a High-Value Target. Its arrival, death, imminent disappearence and escape will be announced both by the Drifter and messages on screen.
- Gambit HVTs
A High-Value Target can appear in Patrol spaces as a World Event. It will begin patrolling the area, attacking both hostile combatants and Guardians alike, until it is killed, or it flees. It will usually be a Major enemy of a faction present in the Destination, with high health and damage, and quickly regenerating Absorption Shields if known to possess them. Occasionally, they can be found defending their chest in a static location, or escorted by allies that roam alongside them. Their appearance, death, imminent disappearance and escape will be announced by messages on the screen.
¥ Indicates that the enemy is escorted by allies.
- Many of The Wanted used to appear as HVTs in Patrol, but were removed with the Vaulting of the Tangled Shore.