Make the cost of using favor less.
Either a fixed mechanical thing so it's automatic or: earn some trinkets to give it a big boost, make it go up with level and the more undead you release the more you get out of your favor exponentially, make it so monsters give more...something?
It's just gotta be done. The system of paying for the favor is good, it is a yang and ying for spirit versus favor but come on now. It's a bit overpriced. We need to make it last longer.
Dragons r Real