Leadership, magic – forget about it...
Education, if the game is intended for players 15+.
P.S. Oh yes, and I almost forgot... the banshee's cry is nonsense, IMO – reducing morale by 1 is the same as with a fatal failure, and losing 10% initiative is, of course, not bad, but when a hero has few levels, it's not desirable to waste an extra one on this skill...

Leadership, if you manage to get the Death Herald, is not bad at all for replenishing the army without a castle; diplomacy allows you to add all joined units to the Temple, so the Temple won't just sit idle. I don't know, I developed without education, and that's not bad either; you can reach level 30 on large maps. Regarding the cry, I'd like to add that it is performed without spending any mana, and at the beginning, when the hero has neither mana nor spells, it's not superfluous to "scream."
P.S. Magic also provides spellcasting speed, which is quite good with dark magic; you cast and instill fear, and then go on your way, reducing the cost of spells, and you can also raise the dead more often.