Culween

Culween is a character in the lore of Dota 2.

Biography
Culween must've invented or was involved in this creation of the spell, since Culween's possessive name is invoked when using it. Thus Culween must be a mage.

Seeing how the young Invoker (who existed during the earliest days when magic was once at its most potent form because 'twas still primarily a mnemonic art) learned the Forge Spirit spell alongside his nine other incantations, wielding them all with his rare and ancient sorcery of invoking, Culween must have existed during the golden age of Magic as well and thus this obscure magician must've been an ancient one too.

In Dota: Dragon's Blood
Culween is not in Dragon's Blood, but the mage's elemental are, conjured by the Invoker to distract Filomena and the Heroes from stopping the planet's cataclysm.

Not only is their creator Culween absent, but the Invoker also doesn't appear to use his elemental orbs to invoke them. But they are beings of fire, as Lina slew one by stealing its flame.

Inheritance
In his youth, the learned Culween's  alongside the nine other spells he currently has, using two Exort orbs and one Quas orb to invoke this spell for casting.

Immortality
Having existed during the old ages when magic was primarily mnemonic, Culween must've been quasi-immortal like the other ancient mages whom Invoker sourced his spells from.

That is, assuming that Culween is still alive today...

Magics
Much like the Invoker, Culween must have had his magic to up spells and wielded the energies of  and  to use invocations. Otherwise, Culween would not be able to conjure (also known as Culween's Most Cunning Fabrications  or Grief Elementals ) who are invoked using two Exort and one Quas. Embodying this strength of Exort's flame and the fortitude of Quas' ice, these elemental spirits are said to be created from naught. They also embody Exort's violence. They have the ability to spit out a that eats through enemy armor, as well as the implied ability to destroy the will, thus they are also known as "Ravagers of Armor and Will" when invoked. Perhaps their ability to ravage the will is the reason why they are called "Grief Elementals" as well. It seems that not all Forged Spirits look the same. This youthful Invoker's subservient elementals take the form of a young dragon hatchling.

Despite this Different appearance, this fiery Dragon whelp is still a Forged Spirit in nature, meaning that it's still an elemental spirit that is forged from naught. It's unknown why Forge Spirits can differ in appearance or what makes them take on different forms.