Brother Corbulo

So, I have use Brother Corbulo for a few games, and  I have a few thoughts.  Brother Corbulo is worth the points, as long as you use him correctly.  Although he is a decent character for challenges, as long as he is not against a PF type weapon, he main strength is keeping other units alive.  In a recent tournament,  Corbulo absorbed 12 plasma wounds that would have otherwise went into a terminator squad (so 5 termies died, instead of all 10).

Cost -
     While he is worth the points, especially when keeping strong units alive, remember that he is adding 105 points, and a kill point to that unit, so if you are not careful you will be putting more eggs into the same basket.

Mobility -
     He has no inherent mobility, so you are going to either want to put him in a vehicle, or put him with a unit strong enough to survive on foot (like terminators).  If he is going to spend more than 2 turns in a vehicle, you are probably better off with a cheaper Sanguinary Priest - if you are not using his 2+ FNP, you are wasting 55 points.  While I have used him successfully with terminators, another good use for him would probably be with a group of Sterngaurd, in a turn 1 Drop Pod assault.  He will significantly prolong the life of the Sterngard unit, as long as you can position him right.

Positioning -
     The hardest part about getting you point's worth from Corbulo is positioning.  Up close, it is easy to make sure he is the closest model to the enemy, but from across the board, it is very difficult, especially if your unit is trying to get cover from a wall (while not giving the enemy a cover save from the same wall).  If he is the closest to the enemy's middle, he probably won't be the closest to shots coming from the table edges.  One way to deal with this is to put the unit close to a table edge, to limit which directions shots can come from (so it is easier to block those directions, although this also limits your unit's threat radius). 
     With terminators, you have another option, which I discovered accidentally.  A unit with 10 terminators and Corbulo is probably a safe place to put your warlord.  This unit would have 3 characters (counting the SGT), so the idea is to position Corbulo where the firepower is most likely to come from, and place your warlord and SGT so that they would be the closest target from other directions - this will allow them to bounce wounds to Corbulo from 2 additional directions (as long as they stay withing 6").