It was over in a a millisecond.
"What's that noise?"
"Don't worry, it's probably just a rat, the place is crawling with them"
The genestealer burst from the vent above, ripping the marine's helmet off in one sweeping motion. Instinctively he caught the lashing front claw in his powerfist, and tried to get a couple of burst off with his bolter, but the beast was too strong and pushed the weapon out of the way, the blasts harmlesly impacting the pipe behind.
Locked in a mortal embrace, they stumbled backwards into the gaping cavern below.
A small diorama of a duel between a Deathwing Terminator and a Genestealer onboard a Space Hulk, built using Games Workshop 30mm figurines.
The base is scratchbuilt from card, paper roll and bits and pieces ripped out of an old printer. The little rat is sculpted from greenstuff. The terminator and genestealer have been modified into their final positions with lots of patience and super glue.