Anti Structure Pad
You can prevent enemy construction around your base while members of your group continue building there.
Mechanics
Section titled “Mechanics”The blocking area expands after placement. It does not remove structures already present. You and your group can still build inside the area if the placement spot is clear.
Enemies cannot place or throw 
TNT from inside the blocking area. TNT
thrown from outside can still enter. The area does not block 
Landmine
placement, though mines still need a clear spot.
Your pads stay in the world when you die and still count toward your building limit after respawn. Destroying a pad frees a place in that limit; leaving the server removes your pads.
Destroying an enemy pad with a melee weapon gives the listed destroy reward. A projectile finishing blow gives 50 % of that reward. Your own pads give no destroy reward.
Unlocking
Section titled “Unlocking”The Other tree in the structure trees offers the pad from level
4. It costs 1 structure point, with no prerequisite item;
see upgrade points for when you earn them. Choosing it excludes
the 
Speed Boost and 
Honeycomb for that life.
Each placement then pays the resource cost separately.