But practically speaking, just throw all the cards at the damage dealer with the lowest number in the party list (the DD with the highest enmity) unless two people are consistently going back and forth between #2 and #3. The "wrong" DD only has to be doing 2.92% more DPS than the "right" DD for them to get more benefit out of the wrong card, and if they've been #2 since before your last card, they are most likely over that threshold.