Some spells for a wizard state that they need an ability check vs. spell save DC (SSDC). I'm not understanding how this is supposed to work.

If the spell says a creature can see through the effect if it passes an Int vs. the SSDC, how does that work? A d20 is rolled by the DM and the Int mod (if any) of the creature is added and it has to beat (be greater than [or equal to?]) my wizard's SSDC (8 + Wis mod + proficiency bonus)?

Note that this is not about how to calculate this SSDC; I already know how to do that.

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    \$\begingroup\$ Welcome! You can take the tour as an introduction to the site and check out the help center for further guidance. Your question was edited in an attempt to make it clearer. Feel free to revert the changes or edit it again if you don't like any of the changes. Good luck and happy gaming! \$\endgroup\$ – Sdjz Mar 28 at 17:03
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    \$\begingroup\$ @enkryptor There is absolutely no call for sarcasm and rudeness here. If you want to help the user, put an answer down below. If you want to mock them, keep it to yourself. Either way, this comment is not appropriate. \$\endgroup\$ – Rubiksmoose Mar 28 at 17:12
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    \$\begingroup\$ Sorry to roll back your question edit, but an answer addresses the wis/int issue and your edit would invalidate their answer. \$\endgroup\$ – NautArch Mar 28 at 18:03
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    \$\begingroup\$ @NautArch I thought invalidating answers was a perfectly alright thing to do, as long as you didn't completely change the meat of the question. \$\endgroup\$ – J. A. Streich Mar 28 at 19:18

Your analysis is correct (mostly).

Minor illusion is a good example of this. The text (PHB 260) says:

... the creature can determine that it is an illusion with a successful Intelligence (Investigation) check against your spell save DC.

If a creature under the control of the DM uses its action to investigate the illusion, the DM rolls the d20, adds the creature's Investigation bonus (or just its Intelligence bonus if it doesn't have a modifier specified for the Investigation skill), and checks if it is greater than or equal to the caster's spell save DC.

If the check is greater than or equal to the caster's spell save DC, the creature determines the illusion is false.

However, Wizards use Intelligence, not Wisdom, for their spells.

The Wizard's spell save DC, therefore, is 8 + [Intelligence modifier] + [Proficiency bonus].

  • \$\begingroup\$ Thanks, I knew it was Int...just a kind of typo. \$\endgroup\$ – Tanstaafl Mar 28 at 17:58
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    \$\begingroup\$ @Tanstaafl No worries, we kind of figured it was, but this answer covered it just in case. FYI if you find an answer that solves your problem you can indicate that by accepting it by clicking the checkmark next to it. Sometimes it is good to wait 24 hours to do so but you are welcome to do it whenever (or not at all) \$\endgroup\$ – Rubiksmoose Mar 28 at 18:07
  • \$\begingroup\$ @Tanstaafl You can, and probably should, change "Wis" to "Int" in your question... It's a good question, and there's really no point in having that there for all time. Just click the "edit" link under your question and edit away. \$\endgroup\$ – Reginald Blue Mar 28 at 19:15
  • \$\begingroup\$ What gives you proficiency on spellsaves? \$\endgroup\$ – Miles Bedinger Mar 28 at 20:18
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    \$\begingroup\$ @MilesBedinger Your class gives you two saving throw proficiencies, if that's what you mean, but a spellcasting class calculates their spell save DC with 8 + [their spellcasting modifier] + [their proficiency bonus]. A spellcaster is always proficient in the spells they cast \$\endgroup\$ – Blake Steel Mar 28 at 20:25

There's no functional difference between rolling an ability check against a spell DC and rolling any other ability check against any other DC; it's just a different person rolling the dice, and the difficulty is coming off your character sheet rather than the DM's notes.

Meeting the DC of a check exactly is in fact a success, as described in step 3 of "The d20" in the introduction to the Player's Handbook (page 7). My group always forgets whether meeting a DC is a success or not, so I remind them, "The guy with the die wins a tie." (And in the case where more than one person are rolling in opposition -- a Contest, per PHB p.174 -- a tie is really a tie, and the situation is not resolved in either character's favor.)


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