The time of war is upon the galaxy of Sirola and two major solar empires face off against one another in this conflict, the first of these empires is Gareldia which is ruled by a standard race of humans. The empire of Gareldia is still filled with numerous races from each planet in its territory but humans are dominant (you can make your own races creatively for this
), they are ruled by a council of 7 whom are from the original 7 planets that began the conquest to form their empire.
The second empire is Zeltia which is ruled by a race of slender very thin formed humanoid aliens, they have long necks thin limbs and small heads. They have black eyes and are also bald but despite their lack of physical strength, they have powerful psionic abilities that compensate for their combat skills some using it to provide them with more durable combat abilities becoming efficient warriors. Zeltia with superior phase based technology had the upper hand in this war until Gareldia decided to try something ingenious, this required them to capture a Zeltian mastermind which were masters of psionics.
Upon successfully capturing the alien psionic master they would extract samples identifying the source of its psionic abilities, it was a gland in their body which they would replicate using genetic technology. Then the process of applying this gland to their own people began, they would create a sort of genetic treatment to allow the body of the test subjects to accept it. However this had a drawback and the treatment would cause certain death for anyone who was given it, so the solution to this problem was a drug created to counter-balance this side effect and it worked for a time.
However about a month into the training of these commandos dubbed the name 'Phantoms' something else began to happen, it was slow at first but the men and women given this drug began to show violent tendencies without provocation. It was wearing on their minds and reducing their ability to think logically, becoming sort of like animals and even worse they were all combat trained killing machines. The message was sent to the capital planet and a sample was sent with it, a drug is being worked on to counter balance this but there have been a few attacks on the research station running this 'Phantom program' and all the phantoms on the station are threatening to attack all the researchers and security watching them.
(So this idea can go multiple ways, it could be some story involving this scenario on the station with a bunch of animal like commandos threatening to attack all the security and scientists or it could skip. If you want to focus past that time it could be when the perfected drug is released, and the phantoms start deployment on various missions throughout the galaxy.)