The wizard in my campaign has the Eye of Vecna and is a yuan-ti, and this means he has suggestion and dominate monster at least once a day. Could he simply suggest to a demon that it reveal its true name? Or force it to?

If so, wouldn't that effectively give him permanent power over the demon, and make a spell like planar binding basically useless?


2 Answers 2


Yes, you can learn a demon's name this way.

Dominate monster could be used to compel a demon to reveal its true name, but the demon gets a saving throw (and most demons have Magic Resistance, so they will have advantage on the saving throw). Since revealing its true name is "obviously harmful" to the demon, suggestion would not be able to compel it in that way.

The most common use for a demon's true name is as part of the 4th-level summon greater demon spell (in Xanathar's Guide to Everything):

At the end of each of the demon’s turns, it makes a Charisma saving throw. The demon has disadvantage on this saving throw if you say its true name. On a failed save, the demon continues to obey you.

Gate can also be used to summon a specific demon whose true name is known — perhaps one too powerful to be summoned and controlled via summon greater demon:

When you cast this spell, you can speak the name of a specific creature (a pseudonym, title, or nickname doesn’t work). If that creature is on a plane other than the one you are on, the portal opens in the named creature’s immediate vicinity and draws the creature through it to the nearest unoccupied space on your side of the portal. You gain no special power over the creature, and it is free to act as the DM deems appropriate. It might leave, attack you, or help you.

Note that in the case of gate, knowing the demon's true name doesn't help you control it; likewise other spells like planar binding or, indeed, dominate monster are not more effective if the demon's true name is known.

This answer has been edited to include new information from Xanathar's Guide to Everything, which includes spells that specifically benefit from knowing a demon's true name.

  • \$\begingroup\$ planar binding is meant to enslave a creature to your will. likewise, a demon's true name is able to control them. you can use gate on their "name" such as "Arcturious, dark general of gehenna" but not their TRUE name, which is a secret. I think you missed the point of the question \$\endgroup\$
    – Nemenia
    Feb 12, 2016 at 19:42
  • \$\begingroup\$ hmm. so now im wondering, do you HAVE to find out a demon's true name to gate it, or can you use the demon's freely given name \$\endgroup\$
    – Nemenia
    Feb 12, 2016 at 19:51
  • 1
    \$\begingroup\$ No, I understood the question, and I understand the lore around true names of demons. Gate specifies that "pseudonym, title, or nickname"s don't work. Without that, gate just opens a portal to the Abyss for one minute; you may or may not get a demon that way. \$\endgroup\$
    – Marq
    Feb 12, 2016 at 19:56
  • \$\begingroup\$ We're having this discussion in two places. I'm deleting my comments from down here to minimize duplication and I'll answer in my response above to you. \$\endgroup\$ Feb 12, 2016 at 20:18
  • \$\begingroup\$ With the edits this has become more comprehensive than the original, so I'll accept this \$\endgroup\$
    – Nemenia
    Feb 13, 2016 at 1:50

Yes, the rules for this are in the Monster Manual

Suggestion just requires a suggestion that sounds reasonable within a sentence or two. You could suggest the following as a very reasonable suggestion:

"I'll make you a deal demon. You tell me your true name so I can protect myself from you on the prime material plane, and I'll release you to wreak havoc on anything you please, excluding me."

On MM pg. 53, there's an excerpt about demons directly related to this, emphasis mine:

Demon True Names

Though demons all have common names, every demon lord and every demon of type 1 through 6 has a true name that it keeps secret. A demon can be forced to disclose its true name if charmed, and ancient scrolls and tomes are said to exist that list the true names of the most powerful demons. A mortal who learns a demon's true name can use powerful summoning magic to call the demon from the Abyss and exercise some measure of control over it. However, most demons brought to the Material Plane in this manner do everything in their power to wreak havoc or sow discord and strife.

However, this also highlights that you would only have some measure of control, not permanent power. The follow up sentence in the description provided highlights that the demon will actively fight you on this, making Planar Binding a requirement to force something into servitude.

On a personal side note: This is why I use Devils instead of Demons. Devils don't like service, but they expect to be rewarded and will willingly follow commands when they are issued. Source is the entry on Devils on MM pg. 66, under the section "Obedience and Ambition".

  • \$\begingroup\$ well that sounds pretty solid. does it detail anything about what kind of power it gives or is it really that vague? \$\endgroup\$
    – Nemenia
    Feb 12, 2016 at 19:45
  • \$\begingroup\$ @Nemenia I think it's referring to existing spells. \$\endgroup\$ Feb 12, 2016 at 19:50
  • 1
    \$\begingroup\$ Yes, the "power" is defined in the gate and planar binding spells. gate is "powerful summoning magic" and planar binding (or dominate monster) can "exercise some measure of control". \$\endgroup\$
    – Marq
    Feb 12, 2016 at 19:54
  • 2
    \$\begingroup\$ No. The true name lets you (via gate) get the demon close enough to cast planar binding. It doesn't help with actually performing the binding. \$\endgroup\$
    – Marq
    Feb 12, 2016 at 19:58
  • \$\begingroup\$ so you still need to have very high level magic to get one for any length of time, even if you know the true name. alright, that seems fair. i think ill give it to this one \$\endgroup\$
    – Nemenia
    Feb 12, 2016 at 19:59

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