Players are headed to the estate of a family of wizards. Looking for some magical defenses they might notice or even trigger if they wander into secure areas. I am aware of:
Sepia Snake Sigil
Symbol of Revelation
Symbol of Scrying
Symbol of Sleep
Symbol of Fear
Anything else of interest? Spells should be no higher than 7th level, ideally permanent (at least until triggered), bonus if they allow authorized persons to avoid activating the effect.
Magic Mouth can be used as an alarm of sorts. The trigger could be someone entering where they are not supposed to be or something similar and the message could simply be someone has entered the room. Since the range of the trigger is 15’ per level the magic mouth does not even need to be on the door that acts as the trigger. It does have to have line of sight but could still be across the room or down a hallway. Another nice thing about magic mouth is that it is an illusion not a abjuration so the rules of having multiple traps within 10 feet do not apply. When I first started gaming there was no alarm spell so this was actually a common tactic.
Don’t forget to use Magic Aura to hide magic traps from detect magic. Unfortunately it is not on the list of spells that can be made permeant, but does have a duration of 1 day per level. Assuming that the caster has the meta magic feat extend this could last almost a month per casting by a sufficiently high level caster. This means that not every magic trap can be hidden this way but the important ones can be covered. If I were the GM I would allow magic aura to be made permanent as a house rule.
Also don’t forget the spell Permanent Illusion. It cost almost nothing to cast and as a 6th level spell the saving throw will be fairly decent. Cast this to conceal a lot of things from casual observation.
When designing traps, keep in mind that people are unlikely to want highly destructive areas of effect going off inside their own homes, even in secure areas. e.g., "We stopped the intruder by burning the house down."
Golems and caryatid columns are affordable, reasonably tough, and appropriately discriminating.
Yep, was definitely planning on having a few golems.
Extraplanar guards and illusions are also good ideas.
Lost Passage, if they've managed to get hold of a samsaran racial spell, would be perfect.
Now that's a fun one I've never seen. It looks like it's intended to be used outdoors (what with the Survival check to avoid getting lost) but most of the penalties also make sense in an indoor environment. Doesn't look like there's a bypass option, though? Of course, I could always build it into a trap with a particular trigger.
Another nice thing about magic mouth is that it is an illusion not a abjuration so the rules of having multiple traps within 10 feet do not apply.
That is neat...
Defenders with contingency. IE hidden in a separate area with dimension door to target location when intruders enter into X room
Rope Trick with an invisible rope(maybe a guardian with invisibility as a SLA). Makes a great ambush pocket or even a trap if overlayed on an empty doorway
Mage's Private Sanctum
While this may be an estate of a family of wizards, don’t forget the mundane defenses. Magic is easily detected and defeated by magic so throw in some old fashioned mundane defenses. One really sneaky thing to do is to have a false magical trap hiding a real mundane trap.
Another way to counter magic is to use magic to contain something so when it is dispelled the real danger is triggered. One trap I used was a magic ceiling holding up a large slab of loose stone. When the players dispelled the ceiling it dropped the stone slab on their heads. It was designed to look like a trap door leading to a hidden chamber but in reality it was just a trap. It was designed to stop those who think all you need to do to deal with traps is have detect magic and dispel magic.
It used to be possible for Guards and Wards to be made permanent. I wonder why that was removed?
Wow! I hadn't noticed the change until you mentioned it. It's cheaper to have a permanent guards and wards spell than it is to use permanency with the individual spell effects--too cheap for the developers' liking I suppose.