How much damage in total is dealt to the player?
Dictate of the Twin Gods is an enchantment that says If a source would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.
Boros Charm has a mode that allows you to give a creature Double Strike until end of turn.
Sixteen damage will be dealt to the player. The doubling effect of Dictate of the Twin Gods only applies after damage is applied to the creature/player, which means you will have to assign 4 out of the 6 initial points of damage to the frostburn weird so that it is destroyed.