It is a time-honored tradition among Wizards. Preparing Time Stop as your 9th level spell so that you can fill a room with time bombs and watch the whole conflagration go off at once like a mischievous kid on Independence Day. Since playing with time invariably results in breaking laws of physics and fantasy, let’s take a look at how this trope was treated in 5th Edition Dungeons & Dragons.

John Cleese named his character “Tim” after forgetting his line in Monty Python and the Holy Grail

The Rules

Time Stop stops time (Player’s Handbook 283):

“You briefly stop the flow of time…”

Time Stop ends if you try to tie a bad guy’s shoelaces together:

“This spell ends if one of the actions you use during this period, or any effects that you create during this period, affects a creature other than you…”

Delayed Blast Fireball explodes when your concentration ends (Player’s Handbook 231):

“When the spell ends, either because your concentration is broken or because you decide to end it, the bead blossoms with a low roar into an explosion of flame that spreads around corners.”

Concentration is broken if you cast another concentration spell (Player’s Handbook 203):

“The following factors can break concentration: Casting another spell that requires concentration. You lose concentration on a spell if you cast another spell that requires concentration. You can’t concentrate on two spells at once.”

Neither Time Stop, Delayed Blast Fireball, nor Concentration appear in the Player’s Handbook errata (2017), so these are the rules we’re working with.

What Does It All Mean?

It comes down to whether you think the Delayed Blast Fireball expands while time is stopped. Either:

It’s possible because the Delayed Blast Fireball explosion does not happen until time resumes at the conclusion of Time Stop; or

because the Delayed Blast Fireball explosion does not happen until time resumes at the conclusion of Time Stop; or It’s not possible because dropping concentration on Delayed Blast Fireball causes an explosion, which triggers Time Stop’s “affect a creature” clause and ends the stasis.

Time and Explosions

The concentration section states that concentration is broken if you cast another spell requiring concentration. It does not require you to drop concentration before commencing concentrating on a new spell. The concentration exchange between spells occurs simultaneously.

This distinction is important because there is no temporal component to the exchange of concentration. A Wizard can weave in and out of concentration spells during Time Stop. Normally, this doesn’t matter because most spells go away when concentration is dropped.

But Delayed Blast Fireball is a different animal. Unlike concentration which is time-agnostic, Delayed Blast Fireball ties its explosion to when concentration is dropped. Was the use of “when” intentionally distinguished from “if” to indicate that a Delayed Blast Fireball will not explode while time is stopped? The flavor given to Delayed Blast Fireball suggests that it is something that happens over the course of time: it “blossoms” into an “explosion” that “spreads.”

What Else is Delayed Blast Fireball Good For?

From a mechanical perspective, if we don’t allow Delayed Blast Fireballs to be stacked during Time Stop, they aren’t any better than regular old Fireball.

Let’s consider both in a vacuum. When Fireball is scaled up to level 7 to match Delayed Blast Fireball, both deal 12d6 fire damage. Delayed Blast Fireball may do an extra 1d6 if the bead hasn’t exploded by the end of your turn, but at the expense of giving your opponent an opportunity to return to sender. The risk is hardly worth a few extra damage.

The real benefit is that you get to hold onto the Delayed Blast Fireball for up to a minute by concentrating. But wait, can’t you already do that by readying a Fireball? Ready is technically a one-turn combat action (Player’s Handbook 193). However, there’s no stated direction for what happens if the trigger does not occur. It just says, “If your concentration is broken, the spell dissipates without taking effect.” Further, there is no instruction for using the spell if the trigger does not occur. To me, this suggests that the spellcaster can maintain their concentration until the trigger occurs, holding the spell in abeyance.

Lead Rules Designer Jeremy Crawford has weighed on the issue of maintaining a readied spell. He says that the spell is lost if not used before the spellcaster’s next turn. While this interpretation may have been the Rules as Intended (RAI), it is not Rules as Written (RAW) because the Player’s Handbook is actually silent on this issue. For what it’s worth, Mr. Crawford acknowledges that he allows spellcasters to use their action on a subsequent turn to maintain the readied spell. I submit this practice is what naturally flows from the text.

So go ahead. Let the Wizard blow stuff up. At least they didn’t prepare Wish.