Hot Gates is a reference to the 480 BC battle of Thermopylae. While some bits like the Athenians taking on the Persian Naval force to help out the Spartans tend to be forgotten, the point is that a small army held out for three days against tens of thousands of Persian soldiers, and then some to buy time for other units to retreat. It's very similar to what Lightning and Co. do at the rift--one brave last stand so that their companions could have a chance to survive and achieve victory.

In the first game I think you had to do quite a bit of the story before it was unlocked in the PP catalog. Import data from the first game ensures you don't have to unlock it again and can use the grind-lover plan from the start....are you sure it's not in the PP catalog? O.o