ネクロマンサー

While no soldier blocks it, every 7 seconds (the first time 9 seconds after it appears; a soldier blocking it restarts the count) it raises up to 4 / 5 / 5 / 6 (Casual / Normal / Veteran / Impossible) Skeletons, with no more than 20 raised Skeletons on the battlefield. It stops raising them near the exit.