Heir of Siberys (Storm)

You have manifested a Siberys dragonmark, the most powerful kind of dragonmark. The magical tattoo appears anywhere on your body. You gain the following benefits:

• Increase your Charisma score by 1, to a maximum of 20.
• When you make an Dexterity (Acrobatics) check or any ability check involving navigator's tools, you can roll a d6 and add the number rolled to the ability check.
• You learn the spell storm of vengeance. You can cast it once without expending a spell slot. The spellcasting ability for the spell is Charisma. You must complete a long rest to regain the use of the spell.