Victorian man Fabian Roy Meharry will spend a minimum of 10 years in jail after he pleaded guilty to 62 child abuse charges.
The offences spanned over nine years and included rape, grooming and child pornography.
Judge Liz Gaynor described the 28-year-old Meharry as “sadistic”, “cruel” and “dominating” before sentencing him on Wednesday.
"It would not be unfair to classify you as a monster of depravity," Gaynor said.
She said Meharry harassed his victims, who were aged between 11 and 17, until they gave in to his "perverted" demands.
In some instances he created online aliases such as "BMX Chick" or "USA Girl". He would pose as his own "friends", who would then help bully the victim into agreeing to his demands.
The court heard how Meharry blackmailed children into sex acts and threatened to publish their explicit pictures online if they didn't do what he said.
On one occasion one of his victims told him she was ending their Skype session so she could go to her own birthday party.
"OK have fun because all your friends will see the videos and pics with your face in it... so you either spare five mins or I will never delete them and I'll send the pics to your mother right now... you have two mins to reply or I'll send them," Meharry threatened her, the court heard.
Gaynor did not accept Meharry’s claim of remorse. She said he sought out victims who were vulnerable because of their age and that "older, more experienced females" would not have been so easily "impressed" by him.
“It was as if you saw the internet as providing you with a vast array of vulnerable teenagers who you could prey upon, exploit and terrorise as the whim took you,” she said.