Constitution +2
Strength +2

The Dark Phoenix can coat its weapon in a flame 3 times per long rest as a bonus action. When landing an attack with a melee weapon, roll an extra d4 for fire damage. This will light the target on fire. Normal fire damage applies.

A dark phoenix has 60ft darkvision in a grey hue.

As a phoenix, you can speak both common and primordial.

As long as your body is intact, you cannot die. When knocked unconscious or reaching 0 Hit Points, roll 3 wisdom saves in place of death saves. On a success, you may retain all memory from your last life. On a fail, you lose all memory.

When an allied creature is knocked unconscious, you may use your action to pass all of your remaining hitpoints on to the creature. You are knocked unconscious in the process.

As a dark Phoenix, your character has a black flame instead of an orange one. And fire created by a dark phoenix is also black. 

Phoenix can live up to 500 year of age before dying of old age. They reach adulthood at around 70 years of age.

As a phoenix, you take less damage from fire.