When I have that out, if an opponent is playing circle protection from red or some other protection cards, will I still deal double damage to them? What if I run a red/blue deck, the blue damage would be doubled as well, correct?
Seems to me the damage would get through for any other color you use if the card is out, but still curious about the protection issue.
{Curse of Bloodletting}
The curse card here does not do the extra damage to the player; it says that the source deals double damage. So as long as the source dealing damage is not red, {Circle of Protection: Red} will not prevent someone from taking double damage from you.