Darius cannot carry his team to victory. If he begins to starve the carries, you can say goodbye to your team's win. During the laning phase, play passively. However, if he manages to get a full combo on you PRE 6, do not let it go unpunished. Combo him right back, and then proceed to farming. You will get hurt, but so will he. Post 6, you may need your jungle to come gank, as there is a big possibility that you may lose the trade (although it is heavily dependent on the character you are playing. Olaf is a great counter to Darius). Building the new scimitar from QSS is a great choice, as once your health is to a point that it is very low and you have full stacks on you, you can just cleanse them off and he only hits you for about 250 damage mid game.