Ultimate Shifting

Your shifter heritage reaches its maximum capabilities. You gain the following benefits:

• Increase your Strength, Dexterity, or Constitution score by 1, to a maximum of 20.
• You gain an additional usage of your Shifting trait, and it is not refreshed until you finish a short or long rest.
• The calculation of temporary hit points you gain from shifting changes. When shifting, you gain temporary hit points equal to 1.5 times your level (rounded down) plus double your Constitution modifier (minimum of 2). 

Adapted from Ultimate Shifting by Shadowthrone