To make your landmines:
Make a doubble Floor (or ground rather..)
Player walks here
X X X < this is the ground
Be Be Be < this is an invisible level
----------------------------------- < this is to seal up leaks
-- is a brush
X is a trigger that trigggers the "land mine"
B is a func_breakable that also triggers the "land mine"
e is an env_explosion - it gets triggered by either the breakable, or the trigger - it explodes, and damages the closest func_breakable - triggering another mine
![:badass:](http://192.241.182.11/images/smilies/badass.png)