Proximity wire mine
From GMod Wiki
This is my first tutorial, it wil teach you how to make a proximity wire mine.
1. Spawn a wire explosive (i recommend the flat bomb) with:
-100 damage -100 blast damage -Remove on explosion checked
2. Spawn a target finder on top of the explosive, i recommend you select it as nano size, so it wont give away the mine position, with:
-Range 100 -Target players -Target NPC -Target Props* -Target Vehicles* -*these options are optional, but they are good when playing war with friends, so you can destroy their vehicles.
3. Wire the value "detonate" from the explosive on the "output: 1" of the target finder.
This means that when the targe finder finds a target, it will activate the command detonate on the explosive, wich will, well, explode!
-Filipegroh