Invasion NPCs

The Invasion event is ran with the help of named mobs. From the in-game help file, here are some of the characters who help you:

Invasion NPCs:

The following NPCs will aid you in your defense of Ruushi. If you
are not sure how to interact with any of them, simply find that NPC
and type 'answer help' for a list of commands which that specific
NPC will respond to.

Watch-captain Christof
Christof is the organizational center of the defense effort. He will
assign you specific tasks and provide vital information. He can be
found somewhere near the Temple of Ruushi whenever an Invasion is
currently active.

Shaker
Shaker is a young but powerful mage, talented in the areas of
wind and astral magic. At Christof's request, he keeps an eye on
Ruushi's defenders in the streets, warning them when they need to
return to Christof for their safety. He is also in charge of
coordinating aerial assaults on the Vl'lakian warlocks.

Tyf
Tyf is a member of the Craftsman's Guild of Aur-Vindi. She
has a special knack for complex mechanical devices, which she
uses for the benefit of Ruushi's defense efforts.

Commandant Vai-shan
Vai-shan is the keeper of Ruushi's combat logs and defense roster.
Whenever an Invasion is over, you should visit her to request your
reward. She is located in the Earthly Egress, far above the temple
of Ruushi.

Krijjkar
Krijjkar is the acting quartermaster for the Ruushi defense. He
can provide you with a number of unique prizes in exchange for
faction points. He resides in the Earthly Egress, near Vai-shan.

For basic information about Invasions, see 'help ruushi invasion'.