6 + 4 (lucky item) = 10 (PASS)
That BFG9000 blast rearranged the cave's structure and contents quite a bit. The bones of the bug's former victims have disintegrated, and all that's left of the bug is that pile of gibs that got pushed back quite a bit from Doomguy's point-blank range shot.
Stage 4 result validated. 3 life points banked (current total 12), 4 flawless victories.
Splat! yuck..