So we have done the Dragon build in part 1 and next up is Aux to Bat (A2B). Both loved and hated by captains everywhere, it allows you to cool down ALL of your abilities, Tac / Eng and Sci (great I hear you say, but there is a catch, there is always a catch) at the cost of ALL of your Aux power.
Your Aux power drives a lot of your abilities to heal your self and do damage with exotic damage abilities (think grav well, tractor beam repulsers etc). The second catch to loosing all of your Aux is you also lose one of the biggest boosts to damage from the rep system, Nukara Offense (and also the defense boost from Nukara Defense if you have it slotted) in highlighted red below as the higher your aux the higher the bonus.

So while there are other ways to keep uptime on abilities (Dragon and Drake) and A2B has its short comings, it is very useful for situations where the ship doesn't allow you to slot enough tactical abilities (i.e. the exploration cruiser, yes I'm looking at you Galaxy class), so it does have its place. It also has the benefit of being cheap (never to be discounted when starting out or starting a new alt). You can earn the doffs for A2B for free without needing to use the exchange (see the end of this post for how).
So how does it work? Well you slot 2x A2B abilities on your ship and one each of the abilities you want to rotate. You will also need some Technician doffs of the type "[Space] Recharge time on bridge officer abilities reduced". When you fire the A2B ability the doffs slotted in your active space roster will reduce the cool down of each ability by the amount displayed (i.e. 10% for purple tech, 8% for a blue, 6% for green etc for each doff)

You can get away with 2 purples (i.e. 20% reduction) depending on the abilities you have, but the 3x purple you will be able to cool down the longer abilities (i.e. DEM @ 2mins, attack pattern omega @ 1:40) down faster. Easiest way is to tune it to what you need for your ship and the abilities you want to run.
A2B in actionSo here I have a Exploration cruiser with a batch of abilities I want to run. I have 3 purple techs fitted and I'm ready to buff up

First I fire off EptW, APB, FAW and DEM

Then I fire A2B which after about a second reduces the cool down on my abilities

Next we wait for the second A2B and EptS to be ready and we fire them off

Now that we have done this you will notice APB and FAW are ready again I wait a few seconds and fire EptW3 with it.

Next I fire the first A2B again, we have come full circle and repeated the process. That is the Aux to Bat build type.
Side note - If I had also fired Polarize Hull, Sci Team, Eng Team and Hazard Emitters they would have also have had their cool down reduced. Thing to remember is to fire off healing abilities first then fire off A2B to get the max out of them before your Aux subsystem is drained reducing their effect.
Doffing the B'Tran - You can get the Doffs for free by completing the Support Colonization Effort doff mission and getting a crit to get a purple otherwise the reward is a blue tech.
http://sto.gamepedia.com/Assignment:_Support_Colonization_Efforts has all the detail.
Next the Drake build type