Still not addressed after 3 years. It seems the "Aggressive Nependeath" and "Normal Nependeath" are counted as 2 different mobs. Solution: Apply the EXP bonus from the card to the Normal Nependeaths instead because there are only 2 aggressive ones on the map. Forgot that the map "Disposed Flower Garden" exists and spawns many aggressive Nependeaths, so this solution is not viable.