[PhilD]

Originally posted by Arryn:
Cost of 10 PD (ten units + a leader, not 10%) is 55.

Cost of 20 PD (20 units + 2 leaders) is 210.

More precisely: cost of going from (n-1) to (n) is always n gold, so that buying (n) PD from scratch costs (n+1)*n/2 gold.

Also, one should keep in mind that PD always start dead center on the battlefield, with no special orders (so that defaults to Attack Closest for non-archers, and Fire Closes for archers, I believe). It might be important if, say, you are Abysia and have PD commanders with a fire aura: if you have non-Abysian troops stationed there, they will typically get burned by the PD commander's aura. So if you're building indie units in a province that might get attacked, it may be a good idea to have a commander and set them apart from the center. (I've lost a good number of troops to this)