Legionary assassin

Legionary assassins are high-end assassins living in the Mojave Wasteland in Fallout: New Vegas. They work for Caesar's Legion and travel in groups of four.

Background
Legionary assassins are small groups of four elite killers for Caesar, led by a Decanus, a Praetorian Guard or a centurion, dispatched to eliminate the Legion's enemies.

First group are composed of:
 * 1x Recruit Decanus (leader)
 * 2x Veteran legionaries
 * 1x Vexillarius

The second group are for most important Caesar Legion's enemies, composed of:
 * 1x Centurion (leader)
 * 1x Prime Decanus
 * 1x Veteran legionary
 * 1x Vexillarius

The last group is for the Caesar Legion's worst enemies, composed of:
 * 1x Praetorian Guard (leader)
 * 1x Veteran Decanus
 * 1x Veteran legionary
 * 1x Vexillarius

Also during these assassination missions, Praetorian Guards are allowed to use firearms additionally or instead of their unarmed weapons.

Characteristics
Legionary assassins begin to appear if the player obtains a Shunned or worse status with Caesar's Legion. They will travel across the wasteland from their original spawn point towards the player's current location, not stopping until they finally encounter the player. As a result, they can end up attacking the player almost anywhere in the wasteland. Assassins may also attack other non-player characters they pass near while searching for the player, such as NCR settlements or traveling merchants (as with all non-player character vs non-player character combat, this only occurs if the player is currently in the same active map cell as the non-player characters).

Legionary assassins typically attack in 4-man groups; a Recruit-Prime-Veteran Decanus, a Legion Vexillarius, one Veteran legionary and after: Legionary assassins may also appear after aiding the Legion's enemies, namely the NCR, by successfully completing the quests Three-Card Bounty, I Put a Spell on You, I Don't Hurt Anymore, or any other quest that improves the reputation of the player with the NCR.
 * a veteran legionary
 * a centurion
 * a Praetorian Guard

They will have weapons and armor depending on your standing with Casear's Legion and your level. They can range from simple 9mm pistols, caravan shotguns and machetes to 12.7mm pistols and sub-machine guns, assault and Marksman carbines, brush guns, thermic lances and super sledges.

As of patch 1.4.0.525, Legionary assassins level with the player, up to level 45. At higher levels this gives them very high health on par with an non-player character companion. Additionally, the Praetorian and Veteran assassin may be equipped with Legion centurion armor instead, making them all the more difficult to kill.

Appearances
Legionary assassins appear only in Fallout: New Vegas.

Bugs

 * Legionary assassins are better equipped with high-tier weapons and armor (e.g. centurion armor, super sledge or thermic lances) from the early game (levels 7-11) instead of the middle or end of the game.
 * Legionary assassins may be carrying blocks of C-4 plastic explosive, but they never seem to be equipped with detonators, making the explosives useless (though highly lucrative for the player after they are defeated).
 * They may occasionally be found setting up ridiculously inadequate attempts at ambushes (such as standing in the middle of the road at Novac staring in one direction), making it easy for the player to walk up behind and get the drop on them.
 * Sometimes the player will engage with and kill one Legionary Assassin, only to find the others a bit further on waiting stationary in a set-piece ambush, even though they were within easy hearing range of the firefight.
 * If the assassins are killed, and the player then waits - Upon dismemberment of a corpse, all corpses will suddenly disappear.
 * Mid-way into an ambush, the Legion Vexillarius will often turn tail and run, leaving the remainder of his men to die.
 * Wearing NCR Ranger Patrol armor seems to prevent legion assassins from appearing even though you have a vilified status with the legion. Just taking off the armor or switching to another armor before entering areas where assassins normally spawns seems to fix this problem.
 * The Legion Assassins will often be aware of the player's exact location prior to attack, regardless of how stealthy the player is, and will run towards you to attack, making a stealthy option impossible.
 * If you fast-travel to Ranger station Charlie and the assassins appear, once they are all defeated, you can go inside the station and sleep for 24 hours. Once you exit, the assassins will attack once again.
 * This can be repeated for an unlimited supply of weapons and ammunition, as well as other items the assassins may be carrying.
 * The assassins are essentially the same actual people at each ambush point, from occurrence to occurrence. The corpse or charred remains of a previous encounter gives you access to the inventory of the non-player character you can see standing in your sights. A body or ash pile previously pilfered can be not "empty," showing the inventory of a new non-player character, but until the new iteration of the same character, the Assassin, is killed, taking the items counts as stealing, and you can be caught at it. You can actually put items into one corpse and remove them from the other.
 * Legionary Assassins can spawn near you after you wait for an hour or two at Nellis, which they shouldn't be able to do. This happened while waiting for Janet to arrive at Nellis to meet Jack during Young Hearts (might be related).