I was DMing a game and eventually set up a scenario where the players had to choose between leaving their wagon, or bringing it to a dangerous place where it could be destroyed.
The enchanter thought it'd be a great idea to use two Glyph of warding spells, one for Touch of Idiocy and one for Suggestion, to lower the will of whoever enters, then suggesting them to leave (which he worded reasonably enough).
Now the problem is the fact Touch of Idiocy is a touch spell with no other save. I'm not sure if the fact a person stands in the area counts as touching, or if the enchanter has to roll for a melee touch attack on a flat footed creature (which is just 10 most of the time)
There are a few other problems (how does suggesting a course of action work for the suggestion spell, decided on cast or in person? Can the enchanter stack the idiocy penalty with more glyphs as it has no label (circumstance, inherent, etc)?) but I can see it being justified as it doesn't affect mindless creatures and it only helps against one person, leaving the wagon vulnerable to future thieves (or even the same thief who later on gets brave again).
Best Answer
Multiple glyphs of warding can't ward the same thing...
The target of the glyph of warding is listed as object touched or up to 5 sq. ft./level, and the spell's description says
This prevents chained glyphs exactly as you describe, and for good reason. For example, were multiple glyphs able to ward a lone tiny box, triggering them all simultaneously creates disastrous consequences for the approaching army—seriously, a tiny box will be picked by someone and opened (especially if it's a shiny box), and if there are hundreds of glyphs of warding on that tiny box then boom—goodbye, army. (To actually run such a trick, try the spell explosive runes instead.)
...And a touch spell stored in a glyph of warding will affect the creature that triggers the glyph
The spell's description says
Emphasis mine. The spell touch of idiocy has as its target living creature touched, so a living creature triggering a glyph storing touch of idiocy will be the target of the spell despite the spell's typical casting method. (By the way, multiple penalties from multiple touches of idiocy—as they're from the same source—shouldn't stack, but ask the DM; a penalty is a little more complicated than a bonus, despite the lengths of those linked entries.)
Although the text isn't specific, it's safe to assume that summoned creatures from a spell glyph aren't random creatures from the summon monster list and instead chosen by the glyph's creator when the glyph is created. Likewise, a suggestion spell held in glyph should offer a suggestion that the caster chooses upon creating the glyph rather than offering a suggestion of the caster's choosing when the glyph is activated.
That said, this is a really expensive way to secure a wagon
A heavy wagon only costs 100 gp. Spending hundreds of gp to protect it is an unusual use of resources. If available, consider hiring some locals to guard it. They'll be thankful for the generous 1 gp per day that you pay them to guard your wagon.