Above ground I only received one white knight spawned as reinforcements. Underground I picked up a couple moles and rune master when they spawned on me, could really have used those above ground. My starting nymph and satyr (or whatever I started with) died quickly while trying to seduce something (my poor TC skills are to blame I'm sure). My cardinal underground did quite well. Not sure how you could get another above ground.
Underground I never really tried to go for the center wiz tower. My gold medal cardinal also had magic relay so having domain was not a problem underground and I thought of making the attempt for the center. Big problem was the lightning storms so I spent most of my time searching outside of the domain. I was working on getting units with lightning immunity (djinns and a few other units). I had managed to enlist the aid of a couple chaos lords, pheonix, dragons and other lvl 3s. Quite a force underground but never made it close to the center.
Fun map... I think I'd have had as much or more fun just trying to make an attempt on the center... maybe making that the goal of the game (first to capture the tower wins) or something like that.