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, Urgash's Call requires Teleport Assault, Dead Man's Curse and Power of Speed. In turn, Mark of the Damned contributes to Tremors, Weakening Strike and Excruciating Strike.

Hellfire (marked *) appears twice in the Complete Skill Tree.

Demon Lord Complete Skill Tree
1Logistics:Pathfinding	2Logistics: Swift Gating			3Logistics: Teleport Assault					Urgash's Call
		Gating: Consume Corpse
					Destructive: Master of Fire		2Destructive: Searing Fires
					Gating: Hellfire*
							Destructive: Mana Burst
				1Sorcery: Soulfire		2Sorcery: Arcane Brillance
1Summoning: Master of Conjuration		2Summoning: Fire Warriors		3Summoning: Elemental Balance
1Machines: Catapult	2Machines: Brimstone Rain	3Machines: Tremors
	Gating: Mark of the Damned
			1Luck: Soldier's Luck		2Luck: Swarming Gate		3Luck: Dead Man's Curse
			Dark: Master of Mind		3Dark: Dark Renewal
		Dark: Weakening Strike
		2Attack: Excruciating Strike				3Attack: Power of Speed
1Attack: Battle Frenzy
1Defense: Evasion	2Defense: Hellwrath	3Defense: Stand Your Ground
Gating: Hellfire*					1Leadership: Recruitment		2Leadership: Gate Master
	2Light: Fire Resistance
1Light: Master of Abjuration					1Enlightenment: Scholar		2Enlightenment: Arcane Exaltation	3Enlightenment: Dark Revelation

Demon Lord Skill Tree Urgash's Call - Logistics, Luck, Attack, Dark		1Logistics:Pathfinding	2Logistics: Swift Gating	3Logistics: Teleport Assault	Urgash's Call
			Gating: Consume Corpse
		Dark: Master of Mind	3Dark: Dark Renewal	3Luck: Dead Man's Curse
Gating: Mark of the Damned	Dark: Weakening Strike
		1Luck: Soldier's Luck	2Luck: Swarming Gate
	2Attack: Excruciating Strike	3Attack: Power of Speed
1Attack: Battle Frenzy
Demon Lord Skill Tree War Machines, Sorcery, Destructive, Summoning			Destructive: Master of Fire		2Destructive: Searing Fires
			Gating: Hellfire
					Destructive: Mana Burst
		Gating: Consume Corpse	1Sorcery: Soulfire	2Sorcery: Arcane Brillance
	1Summoning: Master of Conjuration	2Summoning: Fire Warriors	3Summoning: Elemental Balance
1Machines: Catapult	2Machines: Brimstone Rain	3Machines: Tremors
	Gating: Mark of the Damned

Gating						Demon Lord		#	Cheat Code
						Gating		14	SKILL_GATING
						Unique Demon Lord skill. Imps and Demons/Imps, Demons, Hell Hounds and Succubi/All infernal troops except Devils and Arch Devils/All infernal troops (as well as their upgrades) are granted an ability to gate into the infernal plane to bring reinforcements back to the battlefield. Each unit can gate only once per combat. Newly arrived creatures constitute 25%/30%/35%/40% of the gated ones and will disappear after the end of the combat.
						Perk		#	Cheat Code
						Consume Corpse		58	PERK_CONSUME_CORPSE
						Demon Lord receives special combat ability to consume corpses of fallen creatures to restore mana. Consumed corpses disappear from the battlefield.
						Hellfire		59	PERK_DEMONIC_FIRE
						Creatures under Demon Lord's control are granted a 30% chance to deal additional fire damage on attack. The damage is dependent upon the number of creatures in the stack and the hero's Spellpower. Hellfire drains the Demon Lord's mana.
						Mark of the Damned		60	PERK_DEMONIC_STRIKE
						Demon Lord receives special combat ability to punish the target enemy creature with a powerful Mark of the Damned if that creature is about to attack, retaliate or cast any spell. Once declared, Mark of the Damned is active until next hero's turn. Should target creature remain idle or move without attacking, the Mark will not be performed.
	Ultimate					Description		#	Cheat Code
	Urgash's Call					Gating becomes instant.		98	DEMON_FEAT_ABSOLUTE_GATING