I am wondering if it is possible to use the Symbol spell (PHB p. 280) more than once in close proximity to create a deadly trap, where it deals damage twice per round.
First of all, can the Death version of Symbol cause damage twice within the same round?
From the wording, it seems like it could trigger twice - once when triggered, and another time at the end of the turn:
Once triggered, the glyph glows, filling a 60-foot-radius sphere with dim light for 10 minutes, after which time the spell ends. Each creature in the sphere when the glyph activates is targeted by its effect, as is a creature that enters the sphere for the first time on a turn or ends its turn there.
Death. Each target must make a Constitution saving throw, taking 10d10 necrotic damage on a failed save, or half as much damage on a successful save.
Secondly, can you cast Symbol spells more than once in close proximity to each other on top of that, e.g. Stunning?
Stunning. Each target must make a Wisdom saving throw and becomes stunned for 1 minute on a failed save.
I know this would be a very expensive endeavour because of the Materials cost, but just wanted to know if it's possible to use Symbol in this way to set a rather nasty trap.