New Stygian "Land mine"

The Stygian Empire began to employ a new type of mine across multiple theatres.  Dark Magos of the biologis faction of the Dark Mechanicus had been experimenting in "Flesh Crafting".  The result of which was the "Naga mine".  The Stygian Empire employed these creatures much like a minefield.  The naga's would burrow and nest below ground then burrow up and strike at prey after detecting the sonic vibration emited by the preys movements above ground.  While the naga were extremely effective against infantry they proved to be less so against armor units.  Below is a transcript from an early imperial encounter with a naga.

"We had been selected to recon down towards the river.  The scuttlebutt went that the traitors had pulled beck the previous night to a new defensive position on the other side of the river.  Sgt. Beck didn't believe it as the sentry's had detected movement towards our front.  Either way come dusk they sent us, that is 2nd platoon to find out what was what.  We made it to the ridge near the riverbank and were beginning the climb up slowly and quiet like.  Then there was this sudden rumbling sound and we froze. This massive snake like worm suddenly bursts out of the ground in front of second squad.  It bit a man in two and the bone like razors on it's back cut another two men down before they knew what hit them.  A few of the second boys began to fire but I could see the shots bouncing off of the things hide.  Sgt Beck yelled at us to assist 2nd squad when another rumble began.  A second one of those things was on us.  I fired at it but it was too late for Sgt Beck and three of my mates.  The thng killed them and burrowed back into the ground.  We could feel the ground vibrate as it moved beneath us.  When it came back it got the corporal and that's when I heard the Lt. ordering the retreat.  There had been five of the things on the platoon.  The things chased us back a bit towards our own lines, that's when the Lt. bought it.  Of the seventy or so of us that went out only 42 of us made it back." private Hillman 219th Anglican infantry regiment.