I think the only recommendation I could give is that the Lich should be able to get XP from summoned units battling to encourage that kind of necromantic behavior. As it is, it almost feels like a trap for XP in the long run.
Same goes for using recruited undead enemies when there’s no method to healing them.
Otherwise I love what we have so far. Could also use some proofreading but, seriously, it’s really fun.