Player's Handbook 1, p. 170, "Concentration" - "Spell" says:

"If you are affected by a spell while attempting to cast a spell of your own, you must make a Concentration check or lose the spell you are casting."

Now I have the feeling I played DnD wrong for years - this means if I buff myself with e.g. "Mage Armor" and try to cast "Magic Missiles" the next round, I have to do a concentration check, correct? And someone I buff with another spell, too?

There is no mentioning of the spell affecting me being from someone else or hostile.


1 Answer 1


You've not been playing wrong

What the question quotes is a subsection of the section Concentration that, in part, says, "If something interrupts your concentration while you’re casting, you must make a Concentration check or lose the spell" (Player's Handbook 170 and emphasis mine). Typically, turn 1's casting of the mage armor spell can't interrupt turn 2's casting of the magic missile spell.

That is, when a wizard finishes casting the mage armor spell, the wizard is, indeed, affected by the mage armor spell, but on the wizard's next turn that same now-ongoing and already-been-cast mage armor spell doesn't interrupt the wizard's casting of another spell. Getting a new spell on him in the middle of casting the magic missile spell would be a concern because then that's an interruption, but no interruption is typically caused by the spells that are already present on the caster.

For instance, if the mage armor spell were cast on the wizard at the same time as the wizard was casting a magic missile spell then a Concentration skill check (DC = the mage armor spell's saving throw DC) would be required. (Doing this typically requires the caster of the mage armor spell to ready an action.)

The Concentration subsection Spells is telling casters that it's not only weapon damage and the environment that can interrupt casting spells but also that spells can interrupt the casting spells, too.

  • 1
    \$\begingroup\$ Sounds reasonable. I think as a non-native speaker, I mixed up "affect" and "effect" - the "Mage Armor" spell affects me when I cast it, but what I experience later is the effect of the spell. \$\endgroup\$
    – Blutkoete
    Aug 7, 2020 at 9:27
  • 1
    \$\begingroup\$ @Blutkoete Don't feel bad about that, even most native speakers (myself included) mix up "affect" and "effect" all the time. \$\endgroup\$ Aug 7, 2020 at 13:48
  • \$\begingroup\$ "if the mage armor spell were cast on the wizard at the same time as the wizard was casting a magic missile spell then a Concentration skill check ... would be required." - Oh - really? I would have thought the entry "distracted by a nondamaging spell" relates only to spells that attack the caster. \$\endgroup\$
    – Peregrin
    Aug 8, 2020 at 17:17
  • \$\begingroup\$ @PeregrinTook So far as I can tell, the game doesn't make that distinction, although the DM totally can. I can imagine that, even were you warned first, being told to voluntarily forego a saving throw against—and accept the results of—someone else's spell that you think is probably a mage armor spell (whether because that's what you're told or because your Spellcraft skill check is high enough) while you're in the middle of casting your own magic missile spell in combat would, in fact, be distracting. But, like the answer says, it's a really rare scenario, anyway. \$\endgroup\$ Aug 9, 2020 at 12:19
  • \$\begingroup\$ But casting a spell with a casting time of 1 round can easily get you into trouble, if you are distracted by every spell that affects you. Let's say you cast Summon Monster while your allies cast spells like Prayer, Haste etc on the party. ... - not a very rare scenario ... \$\endgroup\$
    – Peregrin
    Aug 9, 2020 at 13:12

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