Dave Justus wrote:I would expect anyone who goes to the expense of a serious magical trap (permanent, self resetting etc.) would make sure to cover it with a thin sheet of lead.
More likely, magic aura; a sheet of lead could potentially interfere with the trap itself.
In fact, in my own lair, I'd probably scatter trapless magic aura effects all over the place, with false auras of evocation and necromancy and all sorts of fun stuff. Then the actual traps would be magic aura'd into auralessness or, just to screw with intruders, weird crap like divination or conjuration (healing).
But I'm evil like that. >:D
Magically reinforced walls here and there, permanent light spells and/or everburning torches, casting prestidigitation to change the color of the walls, casting arcane mark (the best solution, it is permanent and you can set it to be invisible).
Magical areas, multiple types of magic, or strong local magical emanations may distort or conceal weaker auras.
A arcane mark and a trap with a CL of 5 or less have a faint aura.Start placing Arcane mark at random and one or more of them on the trap and either the characters will slow down to a crawl or they will not be able to sue detect magic to discover traps.
I doubt that there are a lot of party that will go: "I detect magic on the area ahead." After 3 rounds: "There are magical auras, universal school there, there and there." "Good we will avoid them." After walking 60': "Stop, I will check again." Another 3 round waiting, then another 60' and so on.
It could be done, even avoiding the tedium at the table by the simple expedient of saying "We cast detect magic every time we enter a new area and wait to see what we find." But the party speed would become 60' every 4 round. Your minute/level spells will last very little.
BTW, there are easy solutions on the part of the trap builder against people doing that:
- put the trap behind a corner, far away that it is hidden by the wall thickness until you pass the corner but close enough that the people crossing the corner are hit by it.
- place the trap in a deep and narrow niche, possibly hiding the opening with a small layer of plaster. It the trap is far back enough you can't detect it trough the wall, but when you are in front of the opening, if it has the wight properties, it will detect you and trigger.