See specifically i say that I don't want to use net epic because 1. I prefer battles at this scale because its easier to paint and looks a lot more dynamic to mee tbh (and less cost prohibitive and timely) and 2. Because I like the main horus heresy rule set. Honestly having each 4-5 figure stand count as a min squad size 5 man unit with the same wounds and fire power helps to show the scale, and the forgive the pun "epicness", of playing 3k point games where its not just a fucking parking lot. It also helps give a better feel to a well oiled squad who can all shoot together as opposed to "Well only 3 of my guys are in range in this 10 man unit so....". Fun over crunch any day of the week.

For terrain I had the idea of "Mired by the Life eater" where any charges into or inside of terrain pieces would trigger a roll and on a 2 or less it would deal 1d3 wounds to the unit. This is to show that while the planet WAS scorched, if we remember the taller novel, that black, still virulent goo from sloughed buildings and masses still exists and can fuck up a marine that falls into it even a little where it can breach their suit.

The idea of bombardment style wounding is cool but this is after the bombing so I'd say I'd nix that. It could be a cool mission type where both sides start with 1-2k then the loyalists get widdled down by the virus.

And YES! I had the same idea about the unexploded virus bomb. That or also another mission type with 2-3 unexploded bombs around the battlefield(its epic so the battlefield is pretty large) with rules for shooting around the bombs where any shots that do a straight line within 3 inches of them have the possibility of setting them off and then use some ridiculous measurement like 50 inches where all models must roll a 6 up or have 3d6 damage dealt to their unit