I go with solar and sun breakers or heart of praxis fire for both, it used to really own people until they nerfed it all. I still think it's pretty decent though with viking funeral as an opener before you start shooting people because the gun hits will do more dmg for a few seconds which should be plenty to kill them. Fusions are much stronger and will ohk if you stick anyone in PvP. Fire bolt is garbage. But as usual its all preference, so try them all. If you can aim and throw accurately fusion prob best for PvP, although it won't damage multiple enemies close together unless they are like touching then it kills them all. Good luck :)