Wizard: Optional Class features

What are these?

The following list are class features that your dm may either allow you to have in addition to the features you gain from your class or they are options that might replace existing class features

Cantrip Formulas

3rd-level wizard feature
You have scribed a set of arcane formulas in your spellbook that you can use to formulate a cantrip in your mind. Whenever you finish a long rest and consult those formulas in your spellbook, you can replace one wizard cantrip you know with another cantrip from the wizard spell list.