Imp Vanguard
The Imp Vanguard spawns every 10 minutes when the artifact of Origin is active.
Before it spawns, a purple portal-type object will appear.
His sprite is the same as that of the Imp Overlord, but with purple eyes.
He deals poison damage whenever it hits the player. The base poison damage is 1000.
His move set is very much different than that of the Imp Overlord. Imp Vanguard only has the basic attack to smash the player and teleport.
The Imp Vanguard can drop the Imp Overlord's Tentacle item, but not as commonly as the Imp Overlord does.
Bugs
If the Unstable Watch is activated in the same second the Vanguard starts spawning (eg. exactly on the 10 minute mark), multiple portals will appear, spawning multiple Purple Imps and Imp Vanguards. This will also happen if the Unstable Watch is activated at 0 seconds through the use of Enigma.
If you are playing Bandit and you use the ability Smokebomb while the portal is starting to spawn Purple Imps and the Imp Vanguard, it will stop all spawning and the portal will disappear.