Since the Guardian is defensive, the other support cruiser should be offensive
But see, there's the rub so to speak. Most of the support cruisers are not set as defense or offense strictly. The Guardian dispurses damage with Shield Projection but then breaks up enemy formations with repulsion so its really a hybrid (although I will argue later its more of a pure defense support cruiser). The Hoshiko repairs and disables, The Cielo Regen's Shields and directs focus fire, The Overseer Repairs and slows incoming fleets. I would say the Subvertor is really the only true single purpose cruiser as its abilities are purely offense based with no effect on the friendly fleet.
The first thing to decide is should the Domina be a hybrid or a pure offense or defense support cruiser. I would make the argument that the Guardian is in fact a pure defensive support cruiser as it is designed to absorb and prevent damage mainly. As such I would argue that the Domina should be a pure offensive support cruiser. So my ideas for an Advent "lore authentic" Offensive Support Cruiser and its abilities would be something like as follows:
Targets Friendly Frigates, Cruisers & Capital Ships. Limit 5 Targets. Cannot Target Self.
AM Cost- 80, Cool Down 70, Duration 30.
"The Rage of the Unity is channeled into the nearby fleet driving the crews and the ships to the maximum of their abilities"
Increase Weapon Damage 10 %, Acceleration and Max Speed 10%, Armor +2.
Targets Single, Enemy Frigates & Cruisers
AM Cost 80, Cool Down 5, Duration 20.
"The Minds of the enemy are flooded with images of fear and terror inducing them to stop all attacks and flee."
Disables Weapons, Abilities and Passive Regeneration. Boosts Max Speed & Acceleration 50%. (I like the secondary effect as it is basically along the lines of running away as FAST AS POSSIBLE but I am open to removing it from a balance standpoint.)
Im open to suggestions to change these but they were my first crack at some offensive support abilities that had the right feel of the Advent. Obviously I would be open to adjusting exact figures as balance requires as well.