When a natural 1 occurs on a spell attack roll or casting check:

  • Roll d100 on the Spell Fumble Table.
  • Effects may include misfires, feedback, or area distortion.
  • Low rolls (01–25) are the most catastrophic.

Spell Fumble Table (d100):

d100Result
01–05Spell backfires: you take half of its damage (or 1d6 per spell level if non-damaging).
06–10Arcane surge: roll on the Wild Magic Surge table (if available).
11–15Spell fizzles: slot is expended, no effect.
16–20Magical feedback: you are stunned until the start of your next turn.
21–25Catastrophic surge: all creatures within 10 ft take 1d6 force damage per spell level.
26–30Wild misdirection: spell targets a random creature within range.
31–35Your focus shatters: next spell you cast is at disadvantage.
36–40Magical resonance: you cannot cast spells until the end of your next turn.
41–50Your spell sputters: effect occurs at half potency (half damage, half duration, or DM’s ruling).
51–60Your spell echoes: harmless but bright/soundy magical display reveals your position.
61–70Spell rebounds: make a DC 15 Constitution save or suffer a level of Exhaustion.
71–80Your spell destabilizes: the area becomes difficult terrain within 10 ft until your next turn.
81–90Your spell leaks magic: nearest magic item flickers or deactivates for 1 round.
91–95You lose focus: cannot take reactions until your next turn.
96–100Arcane chaos: DM invents a unique misfire (wild effect, summoning, inversion).