The skill tree does not include basic skills unless they are required to progress. Each skill requires every skill touching its box on the left. Hence, Howl of Terror requires Banshee Howl, Power of Speed, Silent Stalker and Corrupted Soil. In turn, Banshee Howl contributes to Banish, Dead Man's Curse and Howl of Terror.

Necromancer Complete Skill Tree
1Defense: Protection	2Defense: Chilling Bones	3Defense: Resistance
	Necromancy: Skeleton Archers
Necromancer Skill Tree Howl of Terror - Logistics, Enlightenment, Attack, Dark		3Enlightenment: Dark Revelation	3Dark: Corrupted Soil	Howl of Terror
1Enlightenment: Scholar	2Enlightenment: Lord of the Undead
	1Dark: Master of Curses	2Dark: Spirit Link
	1Logistics: Pathfinding	2Logistics: Death March	3Logistics: Silent Stalker
1Attack: Battle Frenzy	2Attack: Cold Steel	3Attack: Power of Speed
	Necromancy: Eternal Servitude
			Necromancy: Banshee Howl
				Luck: Dead Man's Curse
Necromancer Skill Tree Sorcery, Destructive, Summoning				Summoning: Banish
		3Sorcery: Arcane Excellence	3Destructive: Secrets of Destruction
1Sorcery: Magic Insight	2Sorcery: Boneward
	1Destructive: Master of Ice	2Destructive: Cold Death
1Machines: First Aid	2Machines: Plague Tent		1Light: Master of Blessings	2Light: Twilight
1Leadership: Recruitment	2Leadership: Herald Of Death		1Summoning: Master of Life	2Summoning: Haunted Mines

Necromancy						Necromancer		#	Cheat Code
						Necromancy		15	SKILL_NECROMANCY
						Unique Necromancer's skill. Allows a Necromancer to raise 5%/10%/15%/20% of fallen enemy living creatures as skeletons.
						Perk		#	Cheat Code
						Skeleton Archers		61	PERK_RAISE_ARCHERS
						Allows a Necromancer to raise Skeleton Archers instead of Skeletons.
						Eternal Servitude		62	PERK_NO_REST_FOR_THE_WICKED
						The Necromancer receives an ability to raise some of the fallen undead creatures in his or her army after combat.
						Banshee Howl		63	PERK_DEATH_SCREAM
						Grants a hero an ability to call upon death itself in combat. All enemy living creatures receive -1 to morale, luck and -10% on initiative.
	Ultimate					Description		#	Cheat Code
	Howl of Terror					Banshee Howl special ability additionally dampens enemy morale by -6.		111	NECROMANCER_FEAT_ABSOLUTE_FEAR