Guile of the Cloud Giant

Source: Bigby Presents - Glory of the Giants

Prerequisite: 4th Level, Strike of the Giants (Cloud Strike) Feat   Implementation: nil requirements

You’ve manifested the confounding magic emblematic of cloud giants, granting you the following benefits:

• Ability Score Increase. Increase your Strength, Constitution, or Charisma score by 1, to a maximum of 20. Implementation: per 5e
  

• Cloudy Escape. When a creature you can see hits you with an attack roll, you can use your reaction to give yourself resistance to that attack’s damage. Implementation: per 5e
  

• You then teleport to an unoccupied space that you can see within 30 feet of yourself. You can use this reaction a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest. Implementation: it uses the interrupt system (reactions) BUT you cant choose a location to teleport to during a reaction. Other options like selecting to move forward or backwards was considered but could cause a bug, or fall into lava etc. So as its a Cloud Giant feat it works like this: on a hit you use your reaction. You go into a cloud form and take half damage for those attacks. On your turn you can leave cloud form (no cost) or teleport within 10 metres (no cost). Your cloud form ends at the end of this turn.