TaintedCore -- a Serpentshrine Cavern (SSC): Lady Vashj Tainted Core Announcer

Zero-configuration addon for the Lady Vashj encounter in Serpentshrine Cavern. Announces when you throw a Tainted Core to a player, and when you have one passed to you.

To find out whether players in your raid have the addon installed, use /taintedcore check.

To actually throw the tainted core, you'll need to use it manually -- this addon only announces once you do.
Hotkeying the following macro ahead of time is a recommended way to achieve this:
#showtooltip
/use item:31088