Can the Artificer cast Enlarge on one of their eldritch cannons to grant the cannon the extra 1d4 damage to its initial damage? Some of us were confused on the official ruling of that spell.

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2 Answers 2


No, since a Tiny Cannon is not a weapon. For Small or larger Cannons, it is up to the DM.

Consider the case of a Tiny cannon held in one hand:

A Small eldritch cannon occupies its space, and a Tiny one can be held in one hand.

The text of the spell says (emphasis mine):

If the target is a creature, everything it is wearing and carrying changes size with it. Any item dropped by an affected creature returns to normal size at once.

Enlarge. The target's size doubles in all dimensions, and its weight is multiplied by eight. [...] The target's weapons also grow to match its new size. While these weapons are enlarged, the target's attacks with them deal 1d4 extra damage.

Hence, if the Artifice that is holding the Tiny Cannon is targeted by the Enlarge/Reduce spell their weapons change in size and gain the additional 1d4 damage. It seems by description that only wielded weapons can get this bonus.

Unfortunately, The Eldritch Cannon is not a weapon:

You've learned how to create a magical cannon. [...] The cannon is a magical object.

Compare the difference in description with actual magic weapons, whose description explicitly state that they are weapons (see for example a Dragon Slayer).

Hence, even if a Tiny Cannon can be held in one hand (by description) it does not qualify for the additional 1d4 damage.

For a Small or larger Cannons, the description of Enlarge/Reduce is lacking details when it comes to the rules about the modified damage of weapons that are not wielded:

You cause a creature or an object you can see within range to grow larger or smaller for the duration. Choose either a creature or an object that is neither worn nor carried. If the target is unwilling, it can make a Constitution saving throw. On a success, the spell has no effect.

See for example the following Q&A: If I cast the Enlarge/Reduce spell on an arrow, what weapon could it count as?

The final decision is hence on the DM.

A DM may rule otherwise.

Since an Eldritch Cannon acts as a weapon, it is used as a weapon, it does damage as a weapon and has the name of a weapon, a DM may reasonably consider it as a weapon.

In the case of a Tiny Cannon held in one hand, considering the Cannon as a weapon grants the additional 1d4 damage.

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    \$\begingroup\$ Further evidence that the cannon is not mechanically a weapon: the Artillerist also has a feature called "Arcane Firearm", which adapts an arcane focus for use by the Artillerist but does not turn it into a weapon, despite being called a firearm. Also, the cannon never makes any attacks anyway (the artificer makes the attack), so casting Enlarge directly on the cannon wouldn't really do anything. \$\endgroup\$ Aug 28, 2021 at 12:38
  • \$\begingroup\$ I think that rather than the Dragon Slayer sword, a more on-point comparison to the Eldritch Cannon would be the Topaz Annihilator from Fizban's Treasury of Dragons, since it's a magical firearm that's basically a disintegration raygun. \$\endgroup\$
    – nick012000
    Nov 9, 2021 at 1:20
  • \$\begingroup\$ @nick012000 When I wrote this answer FTD was not out, and I do not have it yet, so I can not properly cite it. Dragon slayer was the first example coming up in mind, 'cause my intent was to show that a weapon is actually classified as a weapon. \$\endgroup\$
    – Eddymage
    Nov 9, 2021 at 8:07

Yes. Enlarged Eldritch Cannons Gain Bonus Damage.

  1. The eldritch cannon is an object which is a valid target of enlarge.

  2. Enlarge/reduce increases the size of the target's weapons.

  3. The description and naming of both the ballista and flamethrower forms of eldritch cannon indicate they are armed with weapons.

    The cannon exhales fire...

    Make a ranged spell attack, originating from the cannon...

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    \$\begingroup\$ By description of the spell, it seems to me that your 2nd point is valid if the target of Enlarge is a creature: If the target is a creature, everything it is wearing and carrying changes size with it. Moreover, the Eldritch Cannon is not equipped with any weapon listed in the PHB or in the DMG. Furthermore, in the DMG a cannon is described as a Large Object and not as a weapon. \$\endgroup\$
    – Eddymage
    Aug 27, 2021 at 22:17
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    \$\begingroup\$ The word 'weapon' has a pretty specific meaning in the game, and being able to produce spell attacks doesn't have anything to do with it. A magic wand isn't a weapon, and neither is an eldritch cannon. I mean, I would totally allow an enlarged cannon to deal bonus damage if it were at my table, but this reasoning is flawed. \$\endgroup\$ Aug 28, 2021 at 4:35
  • \$\begingroup\$ This makes no sense to me, since the arcane cannon itself can vary in size by discretion of the artificer without having any other effect on the cannon's output. I am DMing for an artificer who does this, depending on the situation, to either carry it or to have it walk about like a small creature. Canon function does not change with size of cannon. \$\endgroup\$ Sep 1, 2021 at 15:20
  • \$\begingroup\$ @KorvinStarmast The damage increase isn't a side effect of changing size. Both the size change and damage increase are effects of the spell. Otherwise I would expect a more 3.5 edition approach where the size increases then you go lookup the resulting damage for the new size category. \$\endgroup\$
    – GcL
    Sep 1, 2021 at 16:27
  • \$\begingroup\$ @Eddymage the target of the spell can be a creature or an object. The language for the damage increase is not contingent on the target being a creature. The only creature specific language in the spell is "If the target is a creature, everything it is wearing and carrying changes size with it." \$\endgroup\$
    – GcL
    Sep 1, 2021 at 16:32

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