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Given glyph of warding, a book, unlimited funds, and enough time, I'd like to create a superbomb.

My goal here is to create a book where, only when I wanted it to, would detonate, dealing 100 fireballs worth of damage to everyone near this extremely explosive book.

The original wording for the trigger I was going to go with would have been a glyph on the cover with the trigger "when this touches the ground" and glyphs on each page with "when this takes fire damage", and then throw it on the ground far away from me.

This doesn't work because the spell targets the creature that triggered the glyph (me in this instance).

If I reword the cover to "when a creature other than [my name] touches the book" and keep the pages at "when this takes fire damage", does this solve the problem? Will the book then target that creature with all 100 fireballs? If not, what have I missed?

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  • \$\begingroup\$ Partial answers are not allowed in comments. See here for more info. \$\endgroup\$ – Rubiksmoose Jul 26 '18 at 19:35
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    \$\begingroup\$ Until on day fifty, halfway through scribing the book, a fly lands on the book and you die in a hellish inferno. \$\endgroup\$ – John Jul 27 '18 at 6:24
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    \$\begingroup\$ rpg.stackexchange.com/questions/108100/… seems highly relevant, since the event that triggers most of the glyphs is also going to destroy the paper. None of the answers there are very satisfactory, because it's a very poorly written spell in general. \$\endgroup\$ – Mark Wells Jul 27 '18 at 17:17
  • \$\begingroup\$ Don't knock a candle over onto it or smoke while casting... \$\endgroup\$ – user47897 Mar 8 at 16:03
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Yes, this would work

The way you have the trigger worded is perfectly valid and will result in the creature getting hit with all 100 fireball spells in/on the book.

I would tweak the pages' trigger to say "when a creature causes these pages to take fire damage" just to be extra clear that the creature that triggers the cover also triggers the pages.

However...you can't move the book more than 10 feet

Glyph of Warding says:

If the surface or object is moved more than 10 feet from where you cast the spell, the glyph is broken, and the spell ends without being triggered.

So, with this trick, not only will you have to spend 100 hours and 20,000 gp on the spells needed, you will also not be able to move more than 10 feet the entire time. And then you have to hope that your enemy comes to you.

Certainly with enough planning, preparation, and a lot of luck this could be a strategic play. However, there is almost no chance that this strategy will work for the average adventurer.

Will using a portable hole help avoid this? Up to the DM.

Object/surface in a portable hole (or other extradimensional space)

It has been proposed that you might be able to get around this by using a portable hole or some other extraplanar storage see (this Q&A). This might work, except a portable hole is 10 feet deep so removing an item from it would still trigger it.

Also, a DM could argue that the extradimensional space of the hole is an infinite distance away from the current plane. Thus, taking it out or putting it in the hole would break the glyph regardless. So this comes down to a DM decision to make that call.

Triggering object/surface while still in a portable hole (or other extradimensional space)

Another way would be to mount it on a surface inside a portable hole. It is very open-ended what is considered a surface for this spell (see this Q&A) but mounting it to the side of the extradimensional space is probably perfectly acceptable. Of course, since you can't move the surface/object out of the space (see previous section) you are not limited to triggering while still inside the hole.

And this should work as expected (assuming you set an appropriate trigger), doing damage so everyone and everything in the blast radius of the fireballs.

However, I would be very cautious since the portable hole is an object made out of cloth per the description:

This fine black cloth, soft as silk, is folded up to the dimensions of a handkerchief.

Thus, it would potentially not be terribly hard to destroy with 100 fireballs worth of damage being triggered inside of/around it (since fireball's radius well exceeds the portable hole's dimensions).

Bottom line: it will be up to the DM if and how well any workarounds work

There are probably other ways around it, but you'll need a DM to likely agree to whatever workaround you come up with. And if they do watch out because...

Sounds like a great tactic for a villain!1

While this strategy is likely never to work for an adventurer, it is perfect for a villain setting a trap. If a DM is happy to let this work for you as a PC, they may be even happier to allow it to work for the evil NPCs as well.


1 - Thanks @Erik

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    \$\begingroup\$ There is almost no chance that this strategy will work for the average adventurer, but almost 100% chance that this strategy will work for the average villain. Be careful what ideas you give your DM. \$\endgroup\$ – Erik Jul 26 '18 at 19:43
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    \$\begingroup\$ I think this portable hole scheme's details depend on the DM, and that's worth noting. (In my understanding of planar physics (hence in my games), a location on an extradimensional plane is ∞ feet away from any location on the Material plane, so it would exceed the 10-foot threshold and explode as soon as it exited the portable hole (or bag of holding or Haversack, or whatever).) \$\endgroup\$ – SevenSidedDie Jul 26 '18 at 20:09
  • \$\begingroup\$ A portable hole folds up like cloth, but is it actually cloth? I wouldn’t think so. And in any event, the walls of the hole aren’t cloth, and with the hole open the only cloth would be on the reverse—where the fireball can’t reach them. \$\endgroup\$ – KRyan Jul 27 '18 at 14:10
  • \$\begingroup\$ @KRyan the first line of portable hole does say "This fine black cloth, soft as silk, is folded up to the dimensions of a handkerchief." This does imply that the hole is made of cloth. It gets a bit weird to think about how that applies when the hole is unfolded, but I think it is fair to point out. Especially since fireball has a 20' radius and bends around corners which means that the flames are going to be raging inside and out of the PH. Given all this, I think it would be a potentially fair call to say that the cloth magic item takes damage from having 100 fireballs set off in it no? \$\endgroup\$ – Rubiksmoose Jul 27 '18 at 14:18
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I agree with the other posters in the sense that

Yes, this would work, but ...

In the section on "Combining Spell Effects" (PHB. 205) it says that when multiple instance of the same spell overlap, only the most potent effect applies.

Now, it is debatable whether this applies for spells with Instantaneous duration (like Fireball) that are triggered at the exact same moment.

... the strength of the effect depends on the DM

So your victim might get hit by one (all overlap), two (first glyph explodes, this triggers the others simultaneously) or 101 fireballs (each instance counts separately).

Personally, I would certainly rule for the first option, maybe the second if I was feeling very generous.

A possible workaround would be to use multiple different spells and combining spell effect glyphs with explosive runes. One could still potentially argue that all these effects stem from the same spell (GoW), so this is not a guaranteed fix.

Of course, the restriction on moving more than 10ft away from the initial location applies too, as given in Rubiksmoose's answer.

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  • \$\begingroup\$ This is a really good point that I hadn't even thought about. +1 Another possibility would be to program some time delay into the trigger potentially to make all the effects not simultaneous. \$\endgroup\$ – Rubiksmoose Jul 27 '18 at 12:20
  • \$\begingroup\$ That might not work, depending on whether the DM allows you to put a time delay on it. The text says "When the glyph is triggered, the stored spell is cast." \$\endgroup\$ – Mark Wells Jul 27 '18 at 13:37
  • \$\begingroup\$ @MarkWells the time delay in this case would have to be in the trigger. Eg "once the fireball spell on the previous page has triggered and 0.5 seconds has passed..." \$\endgroup\$ – Rubiksmoose Jul 27 '18 at 14:24
  • \$\begingroup\$ That in turn may be difficult as the rune may be destroyed by the explosion(s) by that time and destroying a glyph does not automatically trigger it. \$\endgroup\$ – Surpriser Jul 27 '18 at 15:28
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Yes, it (kind of) solves.

The trigger "when this takes fire damage" doesn't involve a creature, you should shift the target to area instead of creature. Another concern should be the fact that the glyph can't be moved more than 10ft from the location you cast the first glyph on the book or the glyph would be broken and the spell would end without being triggered.

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