Curse of the Dragon

You now have the Curse of the Dragon. This curse manifests as a mark left by the dragon on your skin. The mark is in the shape of the dragon that cursed you. It's black and looks like a fresh brand. You gain the following benefits:

• Increase your Constitution and Strength score by 1, to a maximum of 20.
• You gain a number of spells(draconic abilities) based on the element of the dragon that cursed you.
  • You can use dragon's breath as a bonus action.
  • You're able to use these as your own abilities, so no casting or spell slots.
  • Use Constitution for casting purposes.

Unfortunately, this mark also comes with many drawbacks:

• When you use one of the draconic abilities you take damage equal to 1d6(or maybe 1/4 of the damage done)
• When the mark manifests, the DM will choose(roll?) a random number, when you use the draconic abilities that number of times you will be forced to use the spell "Draconic Transformation" as it is written in the sorcerer spell list. (this could also be done with Wisdom saving throws)
  • While transformed, you're possessed by the spirit of the dragon who cursed you.
  • You rampage indiscriminately attacking anyone nearby.
  • You gain a slight boost to your hp(+10 hp?).
  • You can use any of the draconic abilities without receiving any damage.
• Plus a flaw the DM knows about that you don't know.