At what lvl you will be able to find a monarch

[smeer]

Is there a change a monster will drop a monarch (plain, white, non-soc) in nightmare (A1,A2, A3, A4 or A5)?

[krischan]

Is there a change a monster will drop a monarch (plain, white, non-soc) in nightmare (A1,A2, A3, A4 or A5)?
No. They start appearing in hell act 1, e.g. in the Barracks. If you need one, visit cows or the act 3 jungle for lots of easy kills.