from my testing the best i have come up with for a specter so far is nidus for healing/pwr str, with a kuva zarr for lots of aoe dmg, staticor for radiation with fast fire rate good status and aoe, and a sancti magistar for passive aoe healing and passive 20% status negation. i find running nourish is devastating as it gives all allies (teammates,kavats,specters,eximus specters, nekros shadows,etc) viral damage which stacks to give an extra 325% dmg to hp so um....yeah....