Draconic assistant

After a dragon's fall, you can use an incantation which will summon it back from it's death as an ally with it's own thoughts and new memories. If it ever finds out that you killed it, it will rebel. This dragon deals 2d20 damage for a bite attack, a 3d4 damage for a slashing claws, and a 3d10 elemental damage related to the dragon's color. This dragon walks at a speed of 48ft per minute, and has a flying speed of 120ft per minute if not encumbered (700 pounds). It also has 250 hit points or can be rolled by 20d20. The dragon has an instantaneous ability that can be triggered when the dragon takes damage, Draconic Rampage, where all attacks have an added 1d20 for the next hour. After this is used, the dragon and the caster of the spell will need to perform a short or long rest within the next hour, otherwise the caster is dealt 5d10 damage.