The Bullets trailed for most of the game before gaining the upper hand with a Magnay dunk and a lay-up with four minutes left.
If that wasn’t enough to tempt the recruiters, his seventh block of the night with less than a minute left helped his side steady and hold off the visitors.
He finished the night with 19 points and six rebounds to go with his imposing shot blocking.
An evenly balanced contest erupted just before halftime when Bullets power forward Magnay ignited the home crowd with a rapid trio of blocked shots, all on Phoenix star Mitch Creek.
Magnay’s fierce roar after the third antagonised Creek who launched a verbal tirade at his 21-year-old opponent as they headed into the next timeout.
Magnay, with four blocked shots by halftime, had clearly got under under the skin of his more experienced rival.
Still, the Phoenix started the third term with every chance of an upset win.
To that point they had enjoyed great service from bench players Kyle Adnam and Daniel Trist who had four assists and 11 points respectively at the long break.
The Bullets had trouble forcing stops from the Roberson-led offence that shot at better than 50 per cent from the field for three quarters.
Brisbane fell behind by as much as nine points in the third term before beginning their fightback.