So a player is wanting to figure out the cost to setup a trap for a courtyard of a castle. Basically it will consist of two components. The trigger and the -boom-
Essentially the trigger would be a permanent Arcane Eye set to watch over a 100'x100' room. Lining the left and right walls would be some kind item/rune/jiggery every 5 feet which would trigger and shoot a lightning bolt dealing 5d6 damage to anything in it's line of squares. So, 40 of those. Each one would reactivate at midnight, so only 1 blast from each a day.
What do you guys think? Each of those going to be like a command word item of lightning bolt once a day? or what...