Once per long rest you may choose to activate the Rune of Power.
The term power is in the eye of the beholder and may be defined in many ways. This can mean both physically and mentally. Once a day, you can choose to overcome a physical or mental challenge.
Physical: You can choose to overcome a physical challenge by forcing open a lock, barred door, breaking bonds, keeping a boulder from rolling, etc. You also gain advantage on strength checks temporarily and your carrying capacity doubles.
Mentally: Should you choose to overcome a mental challenge, you may overcome difficult puzzles, spell or intelligence based challenges, etc. You gain advantage on Constitution checks and 2d4 temporary hit points.
Just remember this rune is temporary and may only last of one event!