List of sources that affect Spell Save DC

This is a comprehensive collection of all the sources that affect Spell Save DCs, other than proficiency bonus and spellcasting ability modifier.

Flat increases to Spell Save DC

Equipment	Slot	DC Increase	Spell DC Stat-line	Found in Act
Amulet of the Devout	Amulet	+2	High Spellcasting You gain a +2 bonus to Spell Save DC.	3
Armour of Landfall	Clothing	+1	High Spellcasting You gain a +1 bonus to Spell Save DC.	3
Armour of the Sporekeeper	Clothing	+1	Malefic Funghi The wearer gains a +1 bonus to Spell Save DC and when dealing Necrotic damage, they deal an additional 1Necrotic Damage.	3
Caitiff Staff	Main Hand Melee	+1	Arcane Enchantment You gain a +1 bonus to Spell Save DC and Spell Attack rolls.	3
Cloak of the Weave	Cloak	+1	Arcane Enchantment You gain a +1 bonus to Spell Save DC and Spell Attack rolls.	3
Despair of Athkatla	Main Hand Melee	+1	Arcane Enchantment You gain a +1 bonus to Spell Save DC and Spell Attack rolls.	3
Elixir of Battlemage's Power	Coating	+2 or +3	You gain a +2 or +3 bonus to Spell Save DC.	All
Fistbreaker Helm	Headgear	+1	High Spellcasting You gain a +1 bonus to Spell Save DC.	2
Gauntlet of the Tyrant	Gloves	+1	High Spellcasting You gain a +1 bonus to Spell Save DC.	3
Helldusk Gloves	Gloves	+1	Infernal Acuity You gain +1 bonus to Spell Attack Rolls and Spell Save DC.	3
Hood of the Weave	Headgear	+2	Arcane Enchantment You gain a +2 bonus to Spell Save DC and Spell Attack rolls.	3
Infernal Rapier	Main Hand Melee	+1	High Spellcasting You gain a +1 bonus to Spell Save DC.	2
Ketheric's Shield	Off-Hand Melee	+1	Arcane Enchantment You gain a +1 bonus to Spell Save DC and Spell Attack rolls.	2
Markoheshkir	Main Hand Melee	+1	Arcane Enchantment You gain a +1 bonus to Spell Save DC and Spell Attack rolls.	3
Melf's First Staff	Main Hand Melee	+1	Arcane Enchantment You gain a +1 bonus to Spell Save DC and Spell Attack rolls.	1
Robe of Exquisite Focus	Clothing	+1	High Spellcasting You gain a +1 bonus to Spell Save DC.	2
Ring of Feywild Sparks	Ring	+1	You gain a +1 bonus to Spell Save DC.	3
Robe of the Weave	Clothing	+1	Arcane Enchantment You gain a +1 bonus to Spell Save DC and Spell Attack rolls.	3
Staff of Spellpower	Main Hand Melee	+1	Arcane Enchantment You gain a +1 bonus to Spell Save DC and Spell Attack rolls.	3
Staff of the Emperor	Main Hand Melee	+1	Arcane Enchantment You gain a +1 bonus to Spell Save DC and Spell Attack rolls.	3
The Protecty Sparkswall	Clothing	+1	High Spellcasting You gain a +1 bonus to Spell Save DC.	1
Woe	Main Hand Melee	+1	Arcane Enchantment You gain a +1 bonus to Spell Save DC and Spell Attack rolls.	3

Flat decrease to Spell Save DC

Equipment	Slot	DC Increase	Spell DC Stat-line	Found in Act
Wizardsbane Oil	Coating	-3	You gain a -3 penalty to Spell Save DC.	All

Conditional increases to Spell Save DC

Equipment	Slot	Maximum DC Increase	Spell DC Stat-line	Found in Act
Browbeaten Circlet	Headgear	+1	Browbeaten The wearer gains a +1 bonus to spell save DC while  Threatened.	2
Gloves of Battlemage's Power	Gloves	+10	Battlemage's Power When you hit a target with a spell or cantrip that uses a weapon, you gain  Arcane Acuity.	2
Hat of Fire Acuity	Headgear	+10	Fire Acuity Whenever you deal Fire damage, you gain  Arcane Acuity for 2 turns.	2
Hat of Storm Scion's Power	Headgear	+10	Thunderous Acuity Whenever the wearer deals Thunder damage, they gain  Arcane Acuity.	2
Hat of Uninhibited Kushigo	Headgear	+1	Lay Bare Their Weakness After dealing damage with an unarmed attack, the wearer gains a +1 bonus to their spell save DC until the end of their turn.	2
Helmet of Arcane Acuity	Headgear	+10	Battle Acuity Whenever you deal damage with a weapon attack, you gain  Arcane Acuity for 2 turns.	2
Rhapsody	Main Hand Melee	+3	Scarlet Remittance Gain a +1 bonus to Attack rolls, damage, and Spell Save DC for every foe you slay, up to a maximum of +3.	3
The Shadespell Circlet	Headgear	+1	Shadespell While the wearer is obscured in shadow, their spells gain a +1 bonus to Spell Save DC, making them more likely to succeed.	1

Indirect increases to Spell Save DC

Equipment	Slot	Spell DC Stat-line	Found in Act
Birthright	Headgear	Charisma +2, up to a maximum of 22.	3
Boots of Stormy Clamour	Boots	Arcane Echomalefaction When the wearer inflicts a condition upon a hostile creature, they also inflict 2 turns of  Reverberation.[See: Bugs]	1
Braindrain Gloves	Gloves	Mental Interference When you deal Psychic damage, you also inflict  Mental Fatigue for 2 turns.	2
Duke Ravengard's Longsword	Main Hand Melee	Charisma +2	3
Gloves of Baneful Striking	Gloves	Baneful Strike Whenever you deal damage with a weapon attack, the target receives a -1d4 penalty to its Saving throw against your next spell.	1
Gloves of Belligerent Skies	Gloves	Thunderous Conversion When the wearer deals Thunder, Lightning, or Radiant damage, inflict 2 turns of  Reverberation upon the target(s).	1
Hollow's Staff	Main Hand Melee	Heightened Necromancy Creatures have Disadvantage on Saving throws against your necromancy spells.	3
Khalid's Gift	Amulet	Wisdom +1 (up to 21)	3
Ring of Mental Inhibition	Ring	Mental Inhibition When a foe fails a Saving throw against one of your spells or actions, they gain  Mental Fatigue for 2 turns.	2
Ring of Spiteful Thunder	Ring	Spiteful Thunder When the wearer deals damage[See: Bugs] to a  Reverberating creature, it becomes  Dazed unless it succeeds a  Constitution saving throw.	2
Spineshudder Amulet	Amulet	Crackling Resonance When the wearer deals damage with a ranged Spell Attack, inflict 2 turns of  Reverberation on the target(s).	2
Staff of Cherished Necromancy	Main Hand Melee	Heightened Necromancy Creatures have Disadvantage on Saving throws against your necromancy spells.	3