With the new race must enter the new features of the game. I suggest introduction of the new information parameter, though it's name it's up to you. Each unit has a certain information value. Some races have more of it (for example Advent), some have less (Vasari), TEC at medium, while the new race has the greatest values. For different-sized units this value differs. For Titans it's the greatest, then the capital ships and so on. And also depends on the specifics of the ship = ships that deal with information (skills and equipment for target designation , exploration, creating illusions , etc.) get more of this parameter.
When the two groups of ships are in the gravity well, both will be compared for total sum of this parameter. Having a superiority makes possible to use the unique abilities. If armies are tied = there is a chance to neutralize ability of the other. Most of these abilities are with the fourth race. It is known that the fourth race acted in secret from Vasari. Or rather the attack was sudden and no one said it happened. Three abilities come to mind:
1) Blocking access out of a gravity well. That is, until it is active - no one can get out. It does not act on the units themselves - it changes the very reality of the gravitational well changing the laws of space and time. The (1) ability requires superiority. So it is necessary to reduce the army that activated the skill to neutralize it. When the sum of that parameter in the army using that ability will become lower than that of a foreign army, effects of the ability will end early.
2) Blocking communication with command. So that no kind of information can leave the gravity well. For a player this well become a place hidden by fog of war. He loses all control over his units in the well. Units operate on auto depending on the settings and orders given. The calculation of parameter sum is the same as with (1). But! Superiority should be much higher! That is, there must be a very large advantage in numbers. Duration of the effect is less.
3) Covert movement. Army can not be detected when they make a jump to the gravity well. That is, this race has units that are masking the army. Ability (3) does not require superiority. It requires the presence of a certain unit (which is the first to jump to the gravity well).
Advent will be able to develop something similar. That is they will be using technology using this parameter. Offensive developments using this parameter.
TEC to a lesser extent will be guided by this parameter. Some technologies. The middle between defensive and offensive developments.
Vasari are weak with these abilities. They can develop technologies that provide resistance.
Now I want to hear your ideas.