Swindon finished second and will visit Planet Ice in the second play-off fixture on Sunday (April 10, 5.30pm).
Phantoms then tackle Basingstoke Bison away (Sat, April 16, 6.30pm) and at home (Sunday, April 17, 5.30pm) before clashing with Sheffield Steedogs away (Friday, April 22, 7.30pm) and at home (Sunday, April 24, 5.30pm).
Phantoms will have their work cut out to emulate the 2007-08 side that completed a historic treble by winning the English Premier League play-offs.
Current coach Slava Koulikov led Phantoms to a treble of 2018 Autumn Cup, National Cup and Southern Play-Off Championship.
Basingstoke finished seventh in the final table with Sheffield third. The top two from the group goes through to finals weekend in Coventry (April 30-May 1).
The othe group sees Telford (who finished top of the regular season standings) take on Leeds (4th). MK (5th) and Bees (8th).
The play-off games are not covered by Phantoms season tickets, but the ticket prices have been kept the same as the League games. Season ticket holders seat reservations are still honoured during the play-offs.
Phantoms led 2-1 in Swindon after 26 minutes thanks to goals from Tom Norton and Jasper Foster, but they were 5-2 down before a late consolation goal from Corey McEwen.
Phantoms were without captain Will Weldon & Ross Clarke because of injuries, while Billy Thorpe was in Estonia with GB U18s.
The city side fielded back-up netminder Ryan Bainborough, who performed well, but Norton took the man of the match honours.
Nathan Salem scored twice against Raiders with Norton and Jarvis Hunt also on target.