What happens if you store the Simulacrum spell in a Glyph of Warding spell?

Question

I'm looking at the option of storing Simulacrum in an 8th-level Glyph of Warding. My question is how it will determine what creature gets duplicated.

Simulacrum says:

You shape an illusory duplicate of one beast or humanoid that is within range for the entire casting time of the spell.

Glyph of Warding says:

If the spell has a target, it targets the creature that triggered the glyph.

I'm not sure if the quoted section of Simulacrum counts as "targeting a creature". I could basically see two ways this plays out, and I'm not sure which way it should go:

1. You store Simulacrum, targeting yourself, in Glyph of Warding. Whenever the glyph is triggered, it summons a simulacra of yourself as you were when you inscribed the glyph.

2. You store Simulacrum in a Glyph of Warding. When the glyph is triggered, it "targets" and summons a copy of the creature who triggered the glyph. If they are a valid target (humanoid or beast) it creates a simulacra of the target in the state they were in when the glyph was triggered.

Which interpretation is correct?

Answer 1

Simulacrum explicitly targets a beast or humanoid. Simulacrum is an eligible spell to store in a Glyph of Warding, because it's a spell that targets a creature.

The spell must target a single creature or an area.

The target is selected when the spell is being cast. A spell stored into a Glyph of Warding is not "cast" until the Glyph is activated.

When the glyph is triggered, the stored spell is cast.

The Glyph would "target" the creature stepping on the Glyph and create a duplicate of that creature.

Normally, a Simulacrum is friendly to the caster and the creatures that he designates. The problem is, does the creature storing the Simulacrum spell "cast" it, or does the Glyph "cast" it? This is up to DM interpretation though I would lean towards the latter because of the way that Glyph interacts with other summon spells (i.e. - they don't obey the glyph caster).

If the individual can be said to cast it, the Simulacrum is friendly to the caster. If the Glyph casts it, the Simulacrum is not friendly to the caster, and the spell is mute as to what the Simulacrum does (though presumably, it would have the statistics of the creature that it duplicates, which would include languages, mental statistics, proficiencies, etc.). Beyond this, it is up to the DM.

Answer 2

It is your DM's call if Simulacrum is eligible to store

Simulacrum states:

You shape an illusory duplicate of one beast or humanoid that is within range for the entire casting time of the spell.

It is not explicit that the creature copied is the target of the spell. For this to be explicit would require the spell text to refer to the creature as the target for the spell, like in Polymorph, which says

The transformation lasts for the duration, or until the target drops to 0 hit points or dies.

Simulacrum never refers to the creature copied as a target, so it is up to your DM if he want this to work or not.

You can only copy a creature present during glyph creation

The spell description demands that the creature to be copied is within range for the entire casting time, that is during the time when you cast the simulacrum spell in the process of creating the glyph. So you can not create an instant copy of any random beast or humanoid walking by later on. If it were possible to store a Simulacrum, it would need to be of someone who is in range during the original casting.

What about the Snow-Form?

The material component of Simulacrum includes

Snow or ice in quantities sufficient to make a life-size copy of the duplicated creature

With a range of touch and a casting time of 12 hours ...

You shape an illusory duplicate (...) The duplicate is a creature, partially real and formed from ice or snow

Together this strongly suggests that during the casting of the spell, you are forming the shape of the copied creature from snow and ice with your own hands. You are not touching the creature copied for 12 hours straight, as explained in this Q&A.

How would this interact with the glyph? What's missing is the final transformation of your snow-object into a creature, as the spell finishes. What happens with the snow creature in the meantime?

Simulacrum states that if the Simulacrum dies

it reverts to snow and melts instantly.

This indicates that the snow material component is not consumed in the casting, it sticks around in the physical form of the simulacrum, and suggests the snow creature would need to be around at the time of the spell triggering. This means the physical snow-form would need to be preserved.

It is unclear if it would vanish magically until the glyph triggers, or if it would rest near the glyph until it is triggered. It is also unclear if it would be conserved in this state by the glyph, or if would need to be kept in a cold environment to not melt and possibly then make the spell fail. Nothing says so, so likely it would still be around, kept up by the magic of the glyph.

All of this is deep into DM interpretation/ruling territory, as is to be expected by combining two of the most ill-defined and complex spells in the game.