Inferno on the surface.

That's a good idea too, because it's not very good as it is; it's like it's your land, but there are no bonuses. The units aren't particularly strong anyway, so at least give them a bonus – +1 to speed will definitely have a positive impact on clearing out neutral creatures. And it will make the surface much more playable.
It's a shame that this option can't be added to the poll anymore.