Round 1: 4A5JJGG0600200G
Round 2: 4A1H00180A505
Round 3: 4A1J40422J00G
Round 4: 4A9G0G00009A001
Round 5: MAGG420012008002
No restrictions on weapons or BFC usage, though I would recommend choosing either the City of Ry'uul or Village of Khalim maps, as Harbor of Souls feels a bit too forgiving in this case because of how large it is. A time limit somewhere in between 10 and 15 minutes is recommended if you're playing at default game speed.
All rounds were playtested at above nightmare sliders without the BFC, so default nightmare should be quite doable.
Good luck and have fun!