Role-playing Games Stack Exchange is a question and answer site for gamemasters and players of tabletop, paper-and-pencil role-playing games. It only takes a minute to sign up.
Sign up to join this community
This is taken from the description of the Staff of the Woodlands (emphasis added by me):
You can use an action to expend 1 or more of the staff's charges to cast one of the following spells from it, using your spell save DC
What does "using your spell save DC" mean?
From the DMG at "Activating an Item" (p. 141):
A magic item, such as certain staffs, may require you to use your own spellcasting ability when you cast a spell from the item. If you have more than one spellcasting ability you choose which one to use with the item. If you don't have a spellcasting ability... your spellcasting ability modifier is +0, and your proficiency bonus does apply.
(Emphasis mine.)
Thus you calculate your DC as normal: 8 + proficiency bonus + spellcasting ability modifier.
If you don't have a spellcasting ability - and thus have no spellcasting ability modifier - then your spell save DC is just 8 + proficiency bonus + 0. (For the Staff of the Woodlands, which requires attunement by a druid, this is likely only possible for 13th-level Thief rogues, who have the Use Magic Device feature and can thus ignore class requirements on the use of the staff.)
