Neonchameleon
Legend
The first rule of a hybrid assassin is that you only want to use assassin powers every other round. Because that gets best use out of your shrouds.
With my perversity I'm going to suggest Warlord/Assassin. This is because Warlord goes very well as a hybrid with anything. You never use its attack power. The class features are nice - either an initiative buff for the party or perception and insight boost for the party (both fit assassin teams) and you get healing. You use lazy-warlord powers (Direct the Strike, Powerful Warning) so you aren't stat dependent on the Warlord. Double shroud then stab (I recommend the Greatspear as a reach weapon of choice). Hmm... can you Direct the Strike in Shade Form?
Oh, and multiclass to Warlock. Not only are the multiclass feats quite useful, you can then get Shadow Walk for a single extra feat.
With my perversity I'm going to suggest Warlord/Assassin. This is because Warlord goes very well as a hybrid with anything. You never use its attack power. The class features are nice - either an initiative buff for the party or perception and insight boost for the party (both fit assassin teams) and you get healing. You use lazy-warlord powers (Direct the Strike, Powerful Warning) so you aren't stat dependent on the Warlord. Double shroud then stab (I recommend the Greatspear as a reach weapon of choice). Hmm... can you Direct the Strike in Shade Form?
Oh, and multiclass to Warlock. Not only are the multiclass feats quite useful, you can then get Shadow Walk for a single extra feat.
