Over the previous two months,the jury had heard evidence that in the months before Christmas 2016 the men bought ingredients to make home-made explosives after accessing bomb-making videos online.
They then embarked on late-night road trips from Melbourne's northern suburbs to bushland in Clonbinane,off the Hume Freeway,to test explosives;armed themselves with machetes and downloaded Islamic State propaganda.
On the night of December 20,2016,the four were filmed at Federation Square in what prosecutors said was a reconnaissance visit as their planning intensified.
"If you go and look at a place where you might bomb people or stab people,that's planning,"prosecutor Nick Papas,QC,told the jury in his closing address.
"If you buy hydrogen peroxide,knowing what it's about,that’s planning. If you go up to Clonbinane and try and set off an IED[improvised explosive device],that's planning,that's preparing."
Ibrahim Abbas told police he wanted to carry out the terror attack at a public place at a busy time of year,to inflict mass casualties and invoke fear.
"The bigger,the more terror is achieved,and that's the point,"he told officers.
The prosecution case was that the men planned to use bombs and machetes to kill innocent people at Federation Square,Flinders Street Station,St Paul's Cathedral and the Young&Jackson hotel.
The men were willing to die for their beliefs in waging jihad against those they considered disbelievers.
The Australian-born quartet were arrested by counter-terrorism police on December 22,2016 and have been in custody since.
Ibrahim Abbas is a self-radicalised extremist whose foiled plan aimed to seek revenge on the Australian government for its fight to bring down Islamic State in Syria.
He told police after his arrest:"I believe that engaging in these acts is a religious thing and I was at the forefront of this group when it came to ... propagate this message."
But across eight days in the witness box,the young father repeatedly changed his evidence and recollection of events as he seemingly tried to minimise the roles of the other three men he called his"bros".
Defence lawyers for the trio on trial rejected any notion of their participation in a terror plot or agreement,arguing they were nothing but friends.
But Mr Papas said it was inconsistent for Ibrahim to plead guilty to the conspiracy charge and then claim the others weren't part of it.
Prosecutors argued he,Chaarani and Mohamed conspired from October 21,2016 to the day of their arrests,whereas Hamza Abbas became involved in the plot at the start of December.
Hamza,the trial heard,battled learning difficulties at school and his lawyers portrayed him as a"fish brain"whose intellectual limitations meant he never committed to his brother's evil intentions.
Defence counsel Felicity Gerry,QC,highlighted Ibrahim's admission to police that he planned to put an explosive vest on Hamza as a sign the older,influential brother was using his sibling rather than working with him.
"He was to be used as an instrument,not a co-conspirator,"Ms Gerry said of her client.
The three men were remanded in custody to return for a pre-sentence hearing at a later date.