Sadron

Sadron is a character in the lore of Dota 2.

Biography
It was Sadron who must've made the spell or was involved in its creation since their possessive name is invoked when others cast it. Thus Sadron might be a mage.

Seeing how the young Invoker (who existed during the earliest days when spell-casting was once at its most potent form because 'twas still primarily a mnemonic art) learned this Cold Snap spell alongside his nine other invocations, Sadron must have existed during this golden age of magic as well and thus this obscure mage must've been an ancient one too.

Inheritance
In his youth, the learned Sadron's  alongside the nine other spells he currently wields, using three Quas orbs to invoke this spell for casting.

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

But this is just assuming that Sadron is still alive today, that is...

Magics
Much like the Invoker, Sadron might have the power to spells with the cold energies of. Otherwise, Sadron can't have or even cast the invocation (also known as Sadron's Protracted Frisson  or Quas Frigoris ) which is invoked with Quas Trionis.

This spell saps the heat from the victim to freeze them. The names “Protracted Frisson” and “Cold Snap” imply the freeze duration is brief but prolongable via additional attacks.