Ah. Okay. In that case;
Humans
-Turret line blockading nodes, medi, and arm. While it blocks tyrants from reaching anything valuable and quickly dispatches smaller aliens, it a) invites mara or even goon hoppers onto the reactor where they easily chew through the metal unless a human team is there to shoot them, b) wipes out half the base if one structure is destroyed, a luci is fired, a nade is dropped, or a battlefart is cut, and c) doesn't kill anything unless it's right there. Unless humans pursue the alien, it has a 99.9% chance of living if it leaves the immediate vicinity and waltzes right around the corner.
Aliens
-Anything with floor trappers, high-ceiling acids, or hives. Why? Common knowledge among regular alien builders;
1) Trappers have a cone-shaped FOF. On the floor, they're pointless; humans have to step right on them to be effective. On walls/ceilings (especially far from the human) they're very, very effective.
2) Acids are proximity damage, not acid-contact damage. This means that even if the acid particles hit you, the damage is figured on how close you are to the actual tube. High-ceiling tubes = ~1-2 damage per second. Wall-above-or-next-to-the-door tubes = Major HP rapage.
3) Hives are slugs with wings and BP hogs. Simple. Unless the human stops for coffee on his way back to base, there's little to no chance the slooooowwww, build-point sucking hive dwellers will even keep the attacker in sight, let alone catch him and eat him. You can build more effective acid tubes in place of these hives.
