The message was supposed to be read in between the lines, and there was some pretty big spacing inbetween those lines.
Basically, terrain refers to those slight elevation and depressions in the land. Look at Valleyside University or SG4. Look specifically at expanses of land with not many buildings, you'll see that the land level varies, it'll go up a block here, down a block there, and so forth. This adds dimension to chases, and the possibility that maybe, hopefully, your annoying runner will be caught on one of these and fall into your wanting hands.
What I'd recommend is to create these interesting lands is to either a) go around with a small(3-5)ball brush (with voxelsniper) and overlay all the flat land with these balls, and then blend it over, or you can b) raise and lower the ground with the /b e melt and /b e lift commands, but remember to re-smooth/blend the land afterwards
How's that for helpful criticism?
Nintendonuts GibbyMC
EDIT: to make your lives even easier and this post more useful, I went out and captured some example screenshots:
http://imgur.com/zRlwgw8,6vkTJAN,QO0gpQI
Also, sorry for the late response, I was out all weekend :/