Invasion Enemies

From the in-game help file:

Invasion enemies:

The invading Vl'lakian ogres come in a variety of different breeds and
classes. An ogre's breed determines its size and how tough it is to take
down - different breeds of ogres possess vast differences in strength!
The ogre's class determines its abilities and behavior.

The ogres chosen for the Vl'lakian invasion come in five different 
breeds. In order from weakest to toughest, they are:

  uglings, hunchbacks, half-ogres, rockbiters, ogre lords 
  
Each breed of ogre can come in a variety of different classes. Some of
the ogre classes you may find include:

  armored, howling, meatbag, mesmeric, rogue, shaman, shriveled,
  sulfurous, warlock

Each class possesses different strengths, weakness, and behaviors. For
more specific information on each, see 'help invasion enemy classes'.

Watch-captain Christof will tell you which breeds you are allowed to 
attack, and when. You may pick and choose which classes to fight, but 
always pay attention to the breed! Attacking the wrong ogre may allow 
the Vl'lakian spellbinders to capture you, trapping you in their slave 
pits without the ability to teleport for several minutes.

For example, if you are allowed to attack half-ogres, then any of these
ogres would be safe to enter combat with:

  ( armored half-ogre, howling half-ogre, shaman half-ogre )

However, these ogres would NOT count as half-ogres:

  ( armored hunchback, howling rockbiter, shaman ugling )
Always be completely sure of who you're attacking! It is strongly 
advised that you attack the invaders using their breed keyword - for 
example, 'kill 2.ugling', rather than their class keyword. If you
type 'kill rogue', and you accidentally attack a rogue ogre lord 
instead of a rogue ugling, you may be in for a world of hurt...

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