Harbinger plays the role of Carry. Although he is not that a good choice of carry pick, he is still a powerful intelligent hero. His skills blend for his role in his games so thus his ultimate skill that can cast in AoE. The more int he has, the more he is powerful so that the best item for Harbinger is intelligence type items.
The early game item build for Obsidian Destroyer can be the following:
Ironwood Branch – This item grants each attributes for Obsidian Destroyer giving him more strength and toughness to survive the early game plus the intelligence for mana support.
Ancient Tango of Essifation – This item helps Obsidian Destroyer to regenerate when in mid health condition.
Healing Salve – This item helps Obsidian Destroyer to regenerate more fast whenever he is in a low health condition.
Magic Stick – This helps you to counter spell caster enemy heroes.
Empty Bottle – This item requires a Courier to play.
Clarity Potion – This item helps Obsidian Destroyer to regenerate his mana whenever it is in low condition.
Boots of Speed – This grants Obsidian Destroyer movespeed for chasing and escaping.
The mid game item build for Obsidian Destroyer can be the following:
Headdress of Rejuvenation – This may help Obsidian Destroyer for better health regeneration.
Medallion of Courage – This can do the killing faster because of armor degrading.
Magic Wand – This helps you to regenerate your mana and health in an instant depending on its charge.
Power Threads – This grants Obsidian Destroyer more intelligence and both movement and attack speed.
Mekansm – This provides Obsidian Destroyer and his nearby allies armor and hitpoints.
Force Staff – This helps Obsidian Destroyer in chasing and escaping.
The late game item build for Obsidian Destroyer can be the following:
Eul’s Scepter of Divinity – This grants Obsidian Destroyer the ability to cyclone enemies and himself for chasing, setting and escaping.
Dagon – This grants Obsidian Destroyer an ability to instant kill an enemy.
Aghanim’s Scepter – This item improves the ultimate of Obsidian Destroyer.
Guinsoo’s Scythe of Vyse – This grants him the ability of Hex.
Bloodstone – This grants Obsidian Destroyer more mana and health regeneration.