Les Chiens de Guerre

What happens if Tarik uses his Command of "lower the enemy DEF to three" and Succubus uses her Command of "I have DEF 6 against males"? In other words, does Tarik's Command's "unmodifiable" mean that it overrules Succubus' Command?

 good question ... 
examples ....  could tis be possible?
  say a Succubus is in contact  with  a  Pilar of the faith   and decide to  use her order to increase  the defense  to 6 ...  then Tarik  come along  and decide to lower  her defense . 
because  she alrready use the order and she can only activate once in the turn , then she is done  and tarik will hit on 3 or better

 if the sucubus still have  cmd points(din't use the order  it to raise on  her activation )  she could spend it to rise her defense  once Tarik  decided to lower  her defense  on his activation...   don't know  if this is legal ..

is the order of the Sucubuc a free one that she can use even in the activation of a opponent model ... ?...

The first exemple is the good one.
Never forget that Succub can use his order only during her turn.
(This is the same for Tarik).

So Succub can use her power and comes to fight against Tarick with a defense of 6
After this round you can activate Tarik (for exemple) and use his power to lower the defense of succub to 3
and give her good time.

so . it will work the other way arround too ?

Tarick cone a long and decide to lower the defense of the sucubus  on his activation . and hit her at 3  then  when the Sucubus is  activated     she decide to respond  and rise her defense  to 6  ... and hit the prince  were it hurt

no
You can't modify the defense of the Succub after using Tarik's order.
Read again his order.

 yep. I missed  the unmodified bit .... ;D  them she  is doomed againts tarik ...