Necromancer is both a strong card and a fun card. Here's a trick you can do with it!
So, ECs with Unity abilities tend to be stronger, due to the "cost" built in to the Unity identifier. However, note that Necromancer only copies the
ability of the banished human - he doesn't care if the human had a Unity identifier or not. What are some ways to take advantage of this?
Necromancer banishes King TP III to copy that powerful ability. If you have The Deceiver and Necromancer in your deck, you might consider putting King TP III in your reserve, on the off-chance you have Deceiver in your starting hand. King TP III can be an autoblock at the beginning of a game, and if he ends up in your discard pile, Necromancer can banish him later for extra value.
Necromancer banishes Babylonian Siege Army. Sure, Necro can be negated... Unless he was made CBN by Judean Mediums. A potential CBN Bab Siege Army is pretty good!
Actually, Judean Mediums -> Necromancer would work for any autoblock EC, like Abijam, Doeg, Jezebel, Orpah, etc.