Innate Spellcasting. Ombra's innate spellcasting ability is Intelligence (spell save DC 20). They can innately cast the following spells, requiring no material components:

Elusive. No attack roll has advantage against Ombra unless they are incapacitated.   Legendary Resistance (3/Day). If Ombra fails a saving throw, they can choose to succeed instead.   Shapechanger. Ombra can use a bonus action to polymorph into a Small or Medium humanoid they have seen. While in another shape, they lose the Elusive and Legendary Resistance special abilities. Their skills and saving throw modifiers for abilities related to Strengh, Dexterity, and Constitution (including attack rolls) are reduced by -5. Any equipment they are wearing or carrying isn't transformed.