So, I'm going to try and break the OGBM 3.0 list.
list is here:
viewtopic.php?f=83&t=21447&p=414148&hilit=ogbm#p414148This is not about fun, it's about finding the cheesiest, most gnarly and unfair army possible with the current list.
If that army is still balanced and fun to play against, that's a good sign.
So, the basics:
First obvious list jumps out: 3 gargants and one Mega-Gargant. No fancy extras.
40DC on the table, plus powerfields (15 +3D3 + D6 = 23 on average)
Damn hard to extract teeth* from, damn hard to suppress before it's reduced most of your force to stunned and broken formations. Possibly fun to play against in the 'race against time' way.
*sorry, victory points.
Next: 2 support formations per gargant.
Taking the gargant as a good place to start, for a 3k army you're looking at two main options:
3 gargants with 1050pts left over for up to 6 formations and/or upgrades.
With 6 supporting formations that's an average of 150pts per formation.
With 5 it's a bit more respectable: 210pts each
I think you could reach a reasonable activation count of not entirely popcorn with that.
2 gargants with 1650pts left over (for 4 support formations and upgrades)
so. not exactly a small nippy list, but plenty of space for kustom bits and really heavy hitting blocks ( 9 stompas? 4 supa-stompas! mmmmmm)
You'd probably be slightly worse off here then above, since you'll be out activated left right and center, collecting BM's faster then you can paint them and doing so on blocks that simply aren't as tough or as resilient as a gargant.
Your firepower will drop off faster, you'll still have trouble with board control.
Good modelling opportunities though.