Ok, this will be a bit rushed because I typed the entire thing and then lost it :O I have a ctf map where a door will close when either one of the flags is picked up and will only open again if both briefcases are safe in their bases. to do this I used a math_counter with an initial value of 0, a min value of 0 and a max value of 0. It triggers the lockdown on hitting the max value and opens things up on hitting the min value. Both briefcases have 3 outputs leading to the counter, which are: On Pick Up/Add/1 On Return/Subtract/1 On Capture/Subtract/1 It seems to work when testing in single player, but I don't know what it will do in complex situations. Is my logic sound or not? As a final (related) question, what is a good sound to loop for the firing of a rocket engine? I tried using the HL2 sound that steel does, but it gets annoying very fast.