Jarryd Hayne extended the lead four minutes after the restart after man mountain Junior Paulo ran over five Dragons defenders and passed inside to the onrushing NSW fullback.
Matters went from bad to worse for the Dragons when Sio added his second after Thompson spilt the ball on the first tackle.
Rampaging back-rower Manu Ma'u and the outstanding Will Hopoate combined to send over the winger.
Former Manly star Hopoate produced a display full of quality both in attack and defence and must be knocking on the door for a return to the NSW side that is named on Tuesday, three years after his last appearance.
In comparison, Marshall was peripheral figure, who unsurprisingly given his absence from the game, looked off the pace.
The Dragons continued to flag in the second stanza under the huge pressure with Hayne and Chris Sandow pulling the strings.
A Pauli Pauli try just after the hour-mark, converted by Sandow, extended the hosts' advantage before Hayne wrapped up the Eels' biggest ever win over the Dragons with his second of the game seven minutes from time.
-AAP