"These are by far the nastiest explosives you'll come across. You can scatter them around and concern yourself with other matters. As soon as someone steps near one, you'll hear a far-off boom and accompanying shrieks of agony. Use the alt-fire to drop them at your feet. Also, remember where you've dropped proximities or you may fall prey to your own trap. "
A Proximity Detonator is a weapon in Blood, a variation on the Dynamite Bundle. Where Dynamite Bundles go off on impact, the Proximity Detonator will fall to the ground and set, with a signature beep. At that point, it will explode if anyone moves close to the bomb, including the player. This has the advantage of trap-setting (especially in BloodBath), but disadvantage if the player forgets where he/she placed the bomb, or sets it in such a way to prevent forward progress.
AMMO TYPE: Proximity detonator
REGULAR FIRE: Sets and throws a proximity mine
ALTERNATE FIRE: Drops the mine at the player's feet