I noticed that sunbeam allows you to to create multiple lines within a single turn. What's the maximum possible amount of sunbeam lines able to be within one turn? I'm interested solely in the maximum number of beams fired, be that by allies, glyph's of warding, simulacra, etc. However, all of the beams must be fired on one turn, not throughout a round.

For reference, the spell has a casting time of 1 action and states:

A beam of brilliant light flashes out from your hand in a 5-foot-wide, 60-foot-long line. Each creature in the line must make a Constitution saving throw. On a failed save, a creature takes 6d8 radiant damage and is blinded until your next turn. On a successful save, it takes half as much damage and isn't blinded by this spell. Undead and oozes have disadvantage on this saving throw.

You can create a new line of radiance as your action on any turn until the spell ends.


  • Level 20 Character, any combination of multi-classing allowed
  • Only official material published by WOTC in book form is allowed. No Unearthed Arcana
  • Setup is allowed, including any magical items present in the Dungeon Master's Guide or any other source-book. Items only present in campaign books are not allowed.
  • You may have 4 allies at level 20
  • Simulacrum is allowed
  • The allies and any simulacra are allowed to cast spells.
  • One Epic Boon is allowed
  • Anything dependent on RNG, such as the Wild Magic Table, is not allowed.
  • \$\begingroup\$ Somewhat related: "Casting multiple spells in a single round' \$\endgroup\$ Jan 16, 2020 at 21:52
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    \$\begingroup\$ Are you asking about only a single casting of Sunbeam? Or can multiple allies (or simulacra) cast it for more beams? \$\endgroup\$ Jan 16, 2020 at 22:01
  • 1
    \$\begingroup\$ I edited your question a bit, if you feel that was incorrect feel free to change it \$\endgroup\$ Jan 16, 2020 at 22:27

2 Answers 2


Infinite simulacra firing infinite beams with infinite readied actions

You are a Wizard who knows Wish, Simulacrum, and Sunbeam. For setup, you cast Simulacrum on yourself, then have your simulacrum cast Wish to wish for a simulacrum of you. Have the new simulacrum do likewise, and continue doing this until you have as many simulacra as you want. Each simulacrum readies a Sunbeam spell to be released on your signal. You give the signal, and an arbitrarily large number of sunbeams are fired.

(At some point, there won't be enough room for more simulacra within 6 light-seconds of you, so the signal will reach some of them on subsequent rounds, but if you have reached the point where relativity and speed-of-light delays are an issue, the shortcomings of D&D 5e's "physics engine" will be the least of your worries.)

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    \$\begingroup\$ It's not fancy, but it's the largest number I could come up with. \$\endgroup\$ Jan 16, 2020 at 22:32
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    \$\begingroup\$ @Medix2 The infinity in the title is an oversimplification. The "real" answer in the text is "arbitrarily many". \$\endgroup\$ Jan 16, 2020 at 23:01
  • \$\begingroup\$ Ah good, sorry, comment removed \$\endgroup\$ Jan 16, 2020 at 23:08
  • \$\begingroup\$ @ryan If a simulacrum can cast wish on the same turn that it is wished into existence, then it could actually be infinite, not just arbitrarily large. Just make your wish recursive: I wish for a simulacrum of [Wizard] who will immediately repeat this wish and then [thing you want repeated infinitely]. \$\endgroup\$
    – AgentPaper
    Jan 29, 2020 at 20:12
  • \$\begingroup\$ @AgentPaper Using wish that way runs the risk of losing the ability to cast wish. Just creating the simulacrum (via the spell duplication function) is risk-free. \$\endgroup\$
    – T.J.L.
    Feb 19, 2020 at 15:32

I always like to see what I can come up with solo, with no outside help, in one round... Here goes:

I can do 3 lines with sunbeam in one turn.

Lvl 3 Sorcerer, for the Quicken Spell metamagic
Lvl 2 fighter, for Action Surge
Lvl 15 wizard, to be able to cast sunbeam


  1. Quickened spell to cast sunbeam as a bonus action (1)

  2. Action per turn to activate sunbeam (2)

  3. Use Action Surge activate sunbeam again (3)

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    \$\begingroup\$ Sunbeam is on the Sorcerer spell list, no need to multiclass into wizard. \$\endgroup\$
    – Cubic
    Feb 19, 2020 at 15:24
  • \$\begingroup\$ I just like wizards better, and the original build added time stop and glyph of warding, for a 4th line.. But it got to complicated... \$\endgroup\$ Feb 19, 2020 at 17:04

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