I came to this thread from
MegaBearsFan excellent article.
I often kill a barb nest with archers. I'll kill the last guy and on the next turn I just walk in. I have not noticed one time in my current game that I've done this and the barbs have joined me. I killed three nests in a row and didn't get one 'join'.
You could have just be unlucky, but I am assuming that
all your camps were cleared by archers. The UA is not activated until you kill a camp using a melee unit.
Does the coup de grace have to be with a melee unit for the 'barbs have a 67% chance of joining you' thing to work?
Only the first camp. Also use a melee unit to clear the camp when you spot one with a better unit.
The unit you receive is not dependent on the unit that was killed.
Correct. It is based on the last unit you killed
with a melee unit (on a camp). In my current Germany game, I have gotten three different types of units. Sadly, I was not able to farm camps aggressively enough to raise an army.
So you must kill the unit AND take the camp on the same turn?
Only once. Or to change the barb type that will be spawned by future camps.
Do you have to do this with the same unit and does the barb unit have to be physically on the camp?
No, it does not have to be the same unit. Yes, the bard unit has to be killed on the camp tile for the UA to go into effect. If you only use archers for barb hunting, you will never trigger the UA. For the first camp, use your warrior or a scout for the kill. After that, you can stick with archers.
Whatever the encampment spawns with for the first time is the unit you will get when you defeat it in combat. It could be in the game for four hundred turns but the first unit it spawns is a barbarian brute, even when it's been spawning barbarian paratrooper. You defeated and conquered it? You get the barbarian brute. Carry on. Even when that brute has been dead for 200 turns.
That is substantially incorrect. Whatever the encampment spawns with for the
previous time is the unit you will get for the next camp. When you defeat a camped barb in melee combat, you set the next spawn. So if you want a barb paratrooper, kill a barb paratrooper
with a melee unit while the paratrooper is sitting on the camp. The
next camp you clear (which can, and probably should, be empty when you clear it) has a 67% chance of spawning you a paratrooper.
If you have New Random seed preference turned on then simply save the game before going into each encampment. While it is a hassle, it should help you get units when you need them most.
I have my doubts that this works. Did you try it?