There are spells, which can create a bead like object which will explode after a time. Otiluke's Freezing Sphere is the one I am particularly interested in (incidentally for the same bard my earlier question about Destructive Wave was for), as it is rather safer to handle than Delayed Blast Fireball...

Relevant snippets from spell description:

A frigid globe of cold energy streaks from your fingertips to a point of your choice within range, where it explodes in a 60-foot-radius sphere.


You can refrain from firing the globe after completing the spell, if you wish. A small globe about the size of a sling stone, cool to the touch, appears in your hand. [...] You can also set the globe down without shattering it. After 1 minute, if the globe hasn't already shattered, it explodes.

How much cover can block the spell effect?

Example cases to make answering easier:

  • The spell globe is suddenly placed on the table in front of you by a Mage Hand. It may explode at any time. Clever as you are, you cover it with your brass beer mug and wait 1 minute. Did you just foil a level 6 spell? What if you covered it with your cloak? Or a napkin?

  • You, the mighty culinary wizard, cast the spell, put the globe into a jar filled with cream and berries, close it with a lid, and give it to a servant to hurriedly take it to the king's feast. Did you just initiate an assassination, or send out an exquisite ice-cream dessert?


1 Answer 1


Only total cover blocks the spell.

The excerpt we are interested in is in the Areas of Effects section (Player's Handbook page 204) (added emphasis mine).

A spell's effect expands in straight lines from the point of origin. If no unblocked straight line extends from the point of origin to a location within the area of effect, that location isn't included in the spell's area. To block one of these imaginary lines, an obstruction must provide total cover.

And total cover is described on page 196 of the same handbook.

A target has total cover if it is completely concealed by an obstacle.

Notably, cover does not care about how hard the obstacle is: that obstacle provides cover regardless of hardness. The Dungeon Master's Guide provides optional rules for damaging the obstacle providing cover, but this rule still does not allow for an effect to go through cover if it is destroyed, and the spell you mention – freezing sphere – cannot damage objects.

The other spell you mention – delayed blast fireball — has a line specifying that its explosion "spreads around corners", which would allow it to bypass total cover under specific circumstances. Let's say the bead of the spell delayed blast fireball is under a cloak: if there is even a small gap under that cloak, the explosion goes around it and works regardless, which is not what the bead from the spell freezing sphere would do since it does not spread around corners.

What about half cover and three-quarters cover?
Less than total cover is negligible by the spell freezing spehre, since three-quarters and half cover only aid with Dexterity saving throws (and AC) and this spell calls for a Constitution saving throw.

To entertain your example cases:

Case 1. The beer mug blocks the spell, unless you left a gap (the mug was placed at an angle, perhaps), in which case the explosion would go through that gap but only following straight lines: you could control the area of the spell this way. The same case goes with covering the icy bead with a cloak or napkin.

Case 2. Whether you have initiated an assassination attempt depends on how speedy is the servant you gave that jar to and how quickly do they open it, and also on how do they open it. If a minute has passed and the jar is closed: congratulations, you have served an exquisite dessert. If the jar is opened when the time is up, then the blast follows the opening it has available to travel; ironically, the jar could be amployed as a blaster and make the spell have a different area of effect: a (thin) 60-foot line, or a 60-foot cone if well positioned. Chances are, the jar is facing up when this happens and the explosion would look like a volcano in a cartoon spewing ice straight up.

  • \$\begingroup\$ Unfortunately, an explosion by the meaning of these spells lacks any degree of pressure. If it were to be a real explosion (or more precisely, if the spells added anything to use as rules), then objects would be damaged (like how meteor swarms explicitly tells that objects are damaged by the blast) and anything would be flung about away from the blast (like what happens with thunderwave). Spells only do what they tell you: both freezing sphere and delayed blast fireball only damage creatures; the only effects on objects of these two are freezing water and setting flammables on fire. \$\endgroup\$ Apr 5, 2021 at 7:53
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    \$\begingroup\$ @WakiNadiVellir These are the rules presented to us: if you want these magical explosions to behave differently at your table that's your choice and a different story. I can only provide an answer based on the intended function of spells within the system. \$\endgroup\$ Apr 5, 2021 at 7:56

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