What counts as a boss for Nephalem Valor?
When you have stacks of Nephalem Valor bosses drop significantly more loot (Source). What sort of monsters drop extra loot (not just more magical loot from the magic find, but an increased number of items)?
I've noticed the Warden and the Butcher dropping an increased number of items with Nephalem Valor but I haven't seen blue or yellow mobs dropping more.
Solution 1:
It is safe to assume that the Act bosses count as bosses, but what is less clear is if free range bosses count. The Act bosses are:
Act I
Skeleton king. Araneae. The Warden. Butcher.
Act II
Magda. Zoltun Kulle. Belial.
Act III
Ghom. Siegebreaker Assault Beast. Cydaea. Azmodan.
Act IV
Rakanoth. Diablo.
Free range bosses are also described at that link, but it will take research by someone at 60 to answer whether they count (and I am not yet 60). I would note that champions and uniques should not be expected to count, as they are specifically mention differently in the Blizzard post.
Solution 2:
The complete list of bosses with a 'bonus pool' for Nephalem Valor is as follows:
Act I
- The Skeleton King
- Queen Araneae
- The Warden
- Butcher
Act II
- Maghda
- Zolton Kulle
- Belial
Act 3
- Ghom
- Siegebreaker Assault Beast
- Cydaea
- Azmodean
Act 4
- Izual
- Diablo
You'll note that, with the exception of the Warden, the main thing these all have in common is that they have a dedicated 'boss chamber' in which the fight occurs, which you cannot leave once the fight begins, which makes them easy to identify.