This is DiscoBBQ's L4D Gore plugin, just ported to work correctly with L4D2.
Original Thread :
https://forums.alliedmods.net/showthread.php?t=81421
L4D Gore v2.2 by DiscoBBQ
Description:
-Adds tons of blood to L4D2; Be it Single-Player, Versus, or Co-Op!
Installation:
-Place L4D2Gore.smx in your addons/sourcemod/plugins/ folder
-Place gore_config.txt in your addons/sourcemod/data/ folder
All credit goes to DiscoBBQ for making the plugin.
Update V2.5: Elevators and Crescendo events should work properly now (Thanks honorcode23)