My players found the mummy and decided to attack from a distance, which did not help much since the Mummy Lord has an area spell, Insect Plague, which is even worse than the Fireball...

However, I'm now wondering whether the mummy should have been affected at all. The Fireball goes around corners, even in places that one cannot see, but would it enter a sarcophagus that was never opened before? (so one that's still well sealed)

If it does go inside the sarcophagus, would the Mummy at least get advantage on its saving throw roll?

  • 1
    \$\begingroup\$ How can this be a duplicate? The sarcophagus is NOT carried by the Mummy?! \$\endgroup\$ Sep 22, 2016 at 21:48
  • 3
    \$\begingroup\$ @AlexisWilke: If you want to know whether the sarcophagus is affected, it's not a dupe. If you don't care, and only want to know about the mummy, it's a dupe. \$\endgroup\$
    – user17995
    Sep 22, 2016 at 22:24
  • \$\begingroup\$ Regardless if it's a dupe, it's similar enough that it could be folded into the other question. Perhaps made more broad in application? \$\endgroup\$ Sep 23, 2016 at 13:36

2 Answers 2


The ruling on damage depends on how you judge some of the details

From the spell description (Basic Rules p. 90)

Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 8d6 fire damage on a failed save, or half as much damage on a successful one. The fire spreads around corners. It ignites flammable objects in the area that aren’t being worn or carried.

Some ways to peel this onion.


As the DM, you are always in a position to judge whether or not advantage accrues in a situation. If you want to assign advantage on the saving throw, that might be the simplest approach.

Advantage and Disadvantage (Basic Rules p. 4)
Sometimes an ability check, attack roll, or saving throw is modified by special situations called advantage and disadvantage. Advantage reflects the positive circumstances surrounding a d20 roll, while disadvantage reflects the opposite.
A saving throw can be modified by a situational bonus or penalty and can be affected by advantage and disadvantage, as determined by the DM. (Basic Rules, p. 62)
The DM can also decide that circumstances influence a roll in one direction or the other and grant advantage or impose disadvantage as a result (Basic Rules p. 57)

A player can argue that a Dexterity saving throw advantage is negated if the Mummy is (ruled by you) to be Restrained in the sarcophagus (can't move, since it's stuck in there). You don't have to rule that way, but that can account for advantage and disadvantage cancelling each other out.

Restrained (Appendix A, Conditions) The creature has disadvantage on Dexterity saving throws.

You assign advantage based on circumstances.

Making an Attack
Whether you’re striking with a melee weapon, firing a weapon at range, or making an attack roll as part of a spell, an attack has a simple structure. {snip}
2. Determine > modifiers. The DM determines whether the target has cover and whether you have advantage or disadvantage against the target. (p. 72 Basic Rules) (I'll address cover at the end).

Other considerations / versimilitude

  • Is the sarcophagus flammable? If so, it ignites. If not, then it doesn't. If it ignites, damage from the fireball makes sense.

  • If the sarcophagus is sealed, is there a corner to spread around? Likely no, but if it is not sealed, or decrepit, then the Mummy may be exposed to fire flowing into the Sarcophagus. (Around corners, as it were).

  • Do you want to assign HP to the sarcophagus and see if the fireball destroys it? That isn't necessary, as you could just rule flammable/not flammable, but it is a choice if you want to gin up some HP for it based on the DMG section (p. 246-247) that provides HP for things like barrels and carts.

Does the Mummy avoid damage altogether?

You could rule that the sarcophagus provides enough cover so that the fireball can't get to it ... no corners to go around. That's a fair ruling if you rule that the sarcophagus is not flammable, or it is not destroyed, or it is sealed. The Mummy in that case is never in contact with the fire, which would be because the fire didn't spread around the corners to get at the Mummy.

Some problem with the Cover rule in this situation

Do you rule that it has total cover?

A target with total cover can’t be targeted directly by an attack or a spell, although some spells can reach such a target by including it in an area of effect. A target has total cover if it is completely concealed by an obstacle.

The rules for cover are a bit sticky here. While you can say that the sarcophagus completely conceals the mummy from all directions -- and thus does not provide any corners for the fire to go around -- that may not harness the intent of the rule on cover as it is written. It states that some spells (AoE) negate cover. Cover works well against Line of Sight spells, where full cover behind a stone wall blocks the spell, but the AoE provision lets a fireball going off above the wall to spread to the target. Ruling that the sarcophagus is a wall with coverage from all angles fits well enough, but you might not prefer that as that's a soft area in the rules text. You can make a ruling, using the term "cover" in a less "rules mechanics" sense and in a more "normal language" sense.

Make a ruling and play on, based on what makes the most sense to you.


In the real world, sarcophagi are made from stone (with stone lids). In that case, I very much doubt that the mummy would be damaged at all. If your wizard is high enough level, he could cast Telekinesis (5th Level Transmutation). It's good for 1000 lbs, which should be plenty to take the cover off (or better yet, move it 30 feet and tip it over so that the opening is facing you) and blast it with a fire ball.


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