While having the talents Roaring Blaze and Internal Combustion, the Fire Damage of Internal Combustions consumption of Immolates Damage over Time effect is not increased by the 25% Increase of Immolate Damage caused by the effect of Roaring Blaze.
Internal Combustion deals the same amount of damage, it does not deal 25% increased damage from Roaring Blaze's damage increase to the damage of immolate.
"Roaring Blaze" - Conflagrate increases your Immolate, Incinerate, and Conflagrate damage to the target by 25% for 8 sec.
"Internal Combustion" - Chaos Bolt consumes up to 5 sec of Immolate's Damage Over Time effect on your target, instantly dealing that much damage.
For example, without Roaring Blaze active it should deal 440 damage, which it does.
With 25% increase damage from Roaring Blaze, which increases the damage of Immolate - which is the damage base for the damage dealt by Internal Combustion - it should deal 550 damage. However, it doesn't work this way.
Additionally, Roaring Blaze is a debuff that causes the target to take additional damage from Immolate, not a direct buff to Immolate's damage, and thus Internal Combustion doesn't technically change the damage value of the Immolate on the target.