Managed to finally recruit Priam.
He's probably one of the toughest units to recruit outside of DLC units - he has Axebreaker, Lancebreaker and Swordbreaker, as well as Sol and Luna, two VERY useful attacking units.
This basically means even engaging Priam in melee AT ALL is very risky indeed - you lose 50% accuracy if you're using ANY melee weapon due to his three Breaker skills, plus he can heal off any damage you manage to hit with Sol, and deal hefty damage back using Luna.
Not to mention, the grand majority of his army, who number 50 to your 30, are all VERY high leveled, high statted enemies of varied classes, most of which have their leading stat in the early 40s (to put this in comparison, My Unit/Robin is maxed out at 46 str, with mid 30s in other stats).
Really the only way I could do this was flee from his advancing field, hire some Streetpass units that I could afford to lose, and use them as frontline fighters. (Because hell, a PC that i recruited on the train had ASTRA and GALEFORCE.) Pairing up weaker units (read: anything with <80 HP) with the stronger ones (Morgan, My Unit, Panne, Flavia, Yarne and Aversa were by far the best ones here. Emmeryn also managed pretty well, despite only having 68 HP.)
I didn't lose a single of my core army, though I lost two recruited PCs, "King Turtle", a Hero with 58 HP and maxed out skill, "Cienroth", a Sorceror who was far too weak at 48 HP but hit decently with Mire from afar. A third recruited PC came within a hair's breadth of defeat, at 1/80 HP and managing to dodge a shot that had an 87% chance to hit.
All in all, it was an intense and greatly fun map to play.
Fire Emblem Awakening: Paralogue 23, "The Radiant Hero".