This would be a volume, zone, or actor which random jolts of lightning come out of. They would strike at random bsp or static meshes at random points, until a player or projectiles show up. It will search for them and with an increased probability, strike the victim or projectile. If the player is in water, the volume, zone, or actor will have a greater probability to get struck (like in real life). It would be wise for the person to be around more complex geometry than less, to decrease the risk of being struck. It would look and sound like real lightning. It would also strike in random intervals and intensity.
AlphaOne I will start this after the weekend is over.
ZxAnPhOrIaN: I hope that someone would code this before I finish my current map!
Zxanphorian: Good luck AlphaOne!!