Hello Guys!
I would like to ask if a Harbinger (Troubadour + Rogue [no subclass] ) with Crossbow is viable.

I know that Arquebuses and Arbalests are better, but I would like to try playing with a crossbow. My intention is to damage enemies and summon creatures. By the way, what are the best creatures to summon?

Ancient weapons summon + confounding blind + Scourge of Bezzelo (the triple shot crossbow) is great single target DPS and single creature Control, as you will collapse their deflection as well as constantly interrupt them (with crossbow modal + triple hit) . 

 

Biggest issue is that Scourge of Bezzelo comes so late... 

Well, at least it gives an endgame target. 

Crossbows also benefit from the fact that they have a % chance hit to crit that applies to everything as long as you are actively holding that crossbow, so the idea that arbalests or arquebus's are just better than crossbows might be old advice.

I guess that statement does contain the assessment of all the unique arquesbuses, arbalests and crossbows. And indeed the unique crossbows come late and/or are not accessible if you take the "wrong" route with the factions. You have to be pro Furrante to get Fleetbreaker. It is a nice weapon... I don't know why they did that, but it sucks if you want to play with a crossbow and do not like Furrante and what he wants from you.

If you don't care about that then Fleetbreaker is a good weapon choice imo. With Sure-Handed Ila it will be pretty fast to reload, you can add a fire lash with Mith Fyr which works well with the Sneak Attack dmg bonus and so on.

Yes, best summons are the Ancient Instruments of Death (animated Pike + Warbow + Great Sword). 

  

Thanks guys for the tips.