This isn’t really on-colour. Black gets card draw for a price other than mana, such as life loss or sacrifice, but here there’s a significant chance your opponent pays the price instead. It could be a blue-black card, but feels more like blue-red (with the life loss replaced by damage, of course); if made multicolour, its CMC could also be reduced to 3 given the likes of Divination.
You may want to reread those first three words in the rules text.
Edited