1st time DM here. My level 3 party (DnD 5e) used the immovable rod and some rope to escape through the window of a collapsing tower in the latest session. This left the immovable rod out of range of the Sorcerer's mage hand.

The wizard wished to use his spider familiar (re-skinned as a large ant due to arachnophobes in the group) to climb the rope and press the button. At the time the party were being rushed by a group of guards, I made a hasty decision that this was not possible and they ran for cover.

The wizard has since argued that this should have been possible as with a strength score of 2 the familiar has a carrying capacity of 30lb (2x15) & therefore is stronger than the mage hand previously used to carry the rod. I pointed out that as a spell mage hand works differently but agreed that in future this would be possible - with a strength check from the familiar, considering it's a tiny creature attempting to press the button whilst hanging from the rope tied to the rod, 100+ft in the air.

The wizard is unhappy about this, arguing it should be possible without a check. Should I allow the familiar to do things similar to this without a strength check? If it were a simple button on a wall/ the ground, I would be more inclined to allow it.

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    \$\begingroup\$ Why must it be hanging from the rope? Why not stand on the rod & press the button? (It's going to fall, either way...) \$\endgroup\$
    – Adeptus
    Mar 14 at 1:39
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    \$\begingroup\$ Why does the familiar need to be "swinging"? Can't it climb onto the rod, leaving the rope out of the matter? \$\endgroup\$
    – Rad80
    Mar 14 at 9:39
  • \$\begingroup\$ Note that spiders are "tiny" creatures, so their carrying capacity is halved vs. a small or medium creature with the same Str score. So 15 pounds. (Can small characters really carry that much?). Maybe the monster manual has a tarantula in mind, or other spider that's large for a spider. I still agree with the answers that it seems quite reasonable for a familiar to press a button, using multiple legs to generate forces in opposite directions not just using its body weight / inertia. The rope can even go taut if they're still holding it. \$\endgroup\$ Mar 14 at 14:28
  • \$\begingroup\$ What is the relevance of carrying capacity? The Asian Hercules has a carrying capacity of 5000 metrics tonnes, I still wouldn't want to use it to flip a light switch. \$\endgroup\$ Mar 14 at 14:39

2 Answers 2


RAW, Yes

First, for these two features, the rules aren't ambiguous:

Immovable Rod: "Until you or another creature uses an Action to push the button again, the rod doesn't move ..."

Find Familiar: "A familiar can’t Attack, but it can take other ACTIONS as normal."

The button requires an action and a familiar can take actions.


However, whether you "should" or not is entirely within your discretion - you're the DM and you are explicitly given the power to decide what's possible, what's impossible and what requires a check.

If your position is that because the familiar is hanging from the rope by pushing the button it actually just pushes itself away then that's a totally defensible decision. If we were to foolishly use real-world physics, then the button will require a certain force to push and if that force is less than the force needed to push the ant/spider away then that's what will happen.

However, however, if you consistently disallow imaginative solutions like this you are training your players not to use their imaginations. I make no comment on if that is a good thing or a bad thing - some people like gritty realism, some like swashbuckling daring-do.

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    \$\begingroup\$ A note on physics, ant only needs two legs to hold onto a rope. Thus, it can use remaining four to hold the rod and press the button. More than enough of legs to not be pushed away from the rod when pressing the button. \$\endgroup\$
    – Mołot
    Mar 14 at 8:50
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    \$\begingroup\$ @Molot, I'm choosing to believe that the "spider ... reskinned as a large ant" is like one of those ant mimic spiders, giving it even more legs to play with: en.wikipedia.org/wiki/Ant_mimicry \$\endgroup\$ Mar 14 at 18:32

You should allow it.

Can the "ant" climb the rope?

Spider Whatever-that-is Climb: The spider familiar can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

The answer is yes. Can it press the button? Also a yes. Hanging from the rope is not a problem as the familiar can easily move from the rope onto the rod.

Then the familiar can use an action (not really an "action" unless there's combat underway or your table is entirely turn-based) to press the button.

The rule of cool is also on the wizard's favor. Think about how you would feel if you read this scene in a novel.

However, there's one itsy-bitsy problem nobody mentioned. What happens AFTER the button is pressed?

Ask Willie E. Coyote.

With the rod deactivated, I think the wizard will need to be really quick-witted to save the "ant" familiar from being splattered from a 100+ft fall.

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    \$\begingroup\$ Or the wizard can use their action (or a readied action) to dismiss their familiar mid-air, pick up the rod, and use another action to re-summon their familiar. Or you might rule that creatures that tiny are too small to take fall damage, which is true in real life. Terminal velocity for ants is so slow that it's non-damaging. Not sure about a very large spider like a tarantula, which might be the type of spider the monster manual has in mind for a Str of 2 for a 15 pound carrying capacity (str x 15, divided by 2 because tiny). \$\endgroup\$ Mar 14 at 14:24
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    \$\begingroup\$ @PeterCordes it is up to the player to predict they'll need to prevent the familiar from becoming an ichor splatter on the floor. The Q was from a DM's perspective. Also, D&D is not a physics simulator. All creatures fall and take damage. Golden rule and DM fiat are always implied. \$\endgroup\$ Mar 14 at 15:23
  • \$\begingroup\$ Oh right, you said "save" not "catch". So that already covers dismissing and re-summoning the familiar. Yes I know the 5e rules don't say anything about creatures too light to take fall damage so that would be the DM's choice to house-rule that if they wanted. \$\endgroup\$ Mar 14 at 15:26
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    \$\begingroup\$ @PeterCordes A tarantula has an exoskeleton and creatures with exoskeletons are notoriously capable of surviving falls. I would expect any creature with an exoskeleton smaller than... let's say a cat (give or take) to survive a fall at their terminal velocity (meaning they survive any fall from any height). \$\endgroup\$
    – Flater
    Mar 14 at 23:08
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    \$\begingroup\$ @MindwinRememberMonica I was merely adding a possible justification to Peter's supposition of the DM making their own ruling (from comment: "Or you might rule that creatures that tiny are too small to take fall damage, which is true in real life."). If the DM wants to follow RAW and not make their own ruling, it precludes my comment. I wasn't stating that the DM has to deviate. \$\endgroup\$
    – Flater
    Mar 23 at 23:37

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