1. Chaotic Energy: When your Basic Abilities hit an enemy, your Mana regeneration is increased by X% for 6 seconds.
Incinerate: Increases the initial damage of Immolate to X.
Emberstorm: Rain of Fire deals X% more damage to enemies affected by Immolate.
Demonic Gateway: Reduces the cooldown of the teleport to 20 seconds.
4. Backdraft:
Burning Embers: You can store up to 3 charges of Chaos Bolt.
Gathering Power: Passively grants 5% Ability Power. Each Hero takedown increases this bonus by 2% to a maximum of 15%. This bonus Ability Power is reset to 5% on death.
Envenom: Cooldown: 60 seconds Activate to poison an enemy Hero, dealing X damage over 10 seconds.
7. Healthstone: Cooldown: 80 seconds Instantly restore X% of your maximum Health and additional X% of your maximum Health over 6 seconds.
Devastation: Chaos Bolt increases the damage of subsequent Chaos Bolts by x% for 4 seconds. Stacks up to 3 times.
Fel Armor: Reduces the damage taken from non-heroic sources by X% and increases your Health regeneration rate by X%.
10.
13. Conflagrate: Immolate also grants 1 charge of Chaos Bolt when the effect runs out.
Aftermath: Rain of Fire slows enemies by X% for 2 seconds.
Fire and Brimstone: Increases the radius of Rain of Fire by X%.
16.
Charred Remains: When a target dies under the effect of Immolate, the Abiliy refunds its cost and spreads to nearby targets.
Cataclysm: Rain of Fire needs a brief moment to strike, but deals X% more damage.
Mannoroth's Fury: Passively generate 1 charge of Chaos Bolt every 15 seconds.
Ritual of Summoning: Allied Heroes passing through the circle, have their movement speed increased by X% for 3 seconds. This effect can occur only once every 30 seconds per Hero.
20.
First of all, what are those 'Chaos Bolt' charges? What do they do? What you use them for? If it's explained here somewhere then it's not done clearly. Why that isn't his Trait instead of Demonic Circle? You have no idea how many Gul'dan hero concepts I have seen with the Demonic Circle as his Trait. Can't you people come up with anything else than that?!
Secondly and most importantly; he just feels like a very basic Warlock. Not Gul'dan himself but a normal warlock from WoW who looks like Gul'dan, you know what I mean? Now admittedly we haven't seen Gul'dan in real action using a lot of his spells in battle in Warlords of Draenor so he could do anything for all we know but still. This hero concept just feels too basic. Here you could replace Gul'dan with ANY other warlock and it wouldn't matter. Plus I think that this warlock hero concept is too similar to Kael'thas who is also about burst fire damage. I would rather make Gul'dan an Affliction type of Warlock myself to make him different from the other caster heroes but still stay true to the warlock class. And make his skills somewhat more personalized instead of just taking all the spells from the warlock class' spellbook.