I cast wall of force as a sphere (lets say about 1 foot in diameter) at the tarrasque my party is fighting. As it is cutting through the creature's space when it appears, I can choose which side the creature is on.

I choose the inside.

Will I get a beachball-sized tarrasque, crushed to death inside an indestructible wall? Can I use it to completely cut out a creature's heart or decapitate them?


1 Answer 1


Unfortunately, you can't catch 'em all.

While you may be able to encapsulate smaller monsters, the Targets section of the spellcasting rules (PHB p. 204, BR p. 102) state

"To target something, you must have a clear path to it, so it can't be behind total cover."

Since you target a point - you must be able to see that point, and as framed, you cannot currently see inside the Tarrasque.

But let's say you could, for whatever reason. The paragraph continues with,

"If you place an area of effect at a point that you can't see and an obstruction, such as a wall is between you and that point, the point of origin comes into being on the near side of that obstruction."

So while Wall of Force allows the caster to decide whether or not to shunt the creature forward, it ensures that the dome comes into play on the outside of the Tarrasque.

Seamus asked, "Wait... Can't you target a point near the Tarrasque that you can see, but still creates a sphere that intersects the Tarrasque?"

The rules for Area of Effect can be found in the next section of the rules. The rules state,

"A spell's effect extends 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."

  • 21
    \$\begingroup\$ Sigh, first I can't use "Create Food/Drink" to drown someone, now I can't perform unlicensed Wall of Force surgery... ;( Seriously though, thanks! This is one of those situations where, when presented, it's easy to not think about all the clauses and rules on other pages and such. \$\endgroup\$
    – Nanban Jim
    Mar 14, 2017 at 21:30
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    \$\begingroup\$ Ok so I can't cast the spell somewhere I can't see, but the spell implies i could cast it somewhere I can see that the creature is in the occupying space of. Can I cast it over one of his toenails and with the spell wording force him to be on the inside? \$\endgroup\$
    – mephesto
    Mar 15, 2017 at 19:14
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    \$\begingroup\$ @mephesto correct. Wall of Force provides a way to cast it w/in a creature's space by forcing it to one side of the wall. You just need to force it in such a way that the origin is still a legal target. \$\endgroup\$
    – Reibello
    Mar 15, 2017 at 19:15

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