How to cast curse as aura?
Impresence (physical) causes Vulnerability to have no reservation when cast as aura. How can this be done?
It's described right in the same wiki that you linked:
Vulnerability can be turned into an aura by linking it with either Blasphemy Support or Awakened Blasphemy Support
See link here
Blasphemy Support turns hex curse gems into auras when supporting them. That usually reserves 35% of maximum mana. With Impresence equipped, the reservation is 0% (= none).
The easiest way to obtain that gem is by buying it at Clarissa in act 3 as any character.