Magnus & Seducer (in whichever mix you prefer - I like 5 Seducer 3-4 Magnus) is good for sustain, but for higher damage I prefer Julianos plus whatever else you've got that's good for spell damage (Molag Kena is nice, as is 2-piece Torug's Pact).

For lower level characters just questing I prefer the sustain of Seducer/Magnus, but for higher level characters that need to be able to squeeze out more DPS I prefer Julianos.