His affinity weapon is the judicator and his alt-form is the vhoscythe. Noxus is probably the trickiest hunter control-wise. His judicator bounces on walls and works well in tunnels and closed space because it keeps going until it hits a hunter escapes to the sky, or runs out. If Noxus charges it, he can freeze the other hunter in ice and make them vulnerable for 5 seconds. This allows time for at most 4 shots with the judicator.
Strategy
Noxus should attempt to freeze other players and then finish them off with a headshot using the Judicator. To headshot a character frozen while transforming into their Alt. form, shoot at where there head would usually be, not at where it is. Your shots will only hit if you aim at where they would be if they were standing still. Freezing easily disposes of Alt. forms as they need to close in to damage you.
Chasing after a fleeing enemy with a charged Judicator can be fatal. As they will often fire shots at you as they run.
When freezing players using Trace, it is often a wise move to stand behind him. As many players will gear up for a headshot using the Imperialist when the freeze wears off.
