Mid plat here, 63% winrate on 140+ games.
As darius you mainly need to focus on punishing enemies as this is one of his clear strengths. Your early level extended trades are really strong because of your passive, but his main weakness is that a lot of players go too ham early, overextending and getting caught by a jungle gank. Try to find out what side the enemy jungler started, and place vision accordingly. Try not to let the wave push to you early to avoid a level 2/3 gank, and go for a level 2 or 3 trade yourself when the wave is pushed towards your side. The key to winning trades is often matchup dependant, so this can require some experience on the champ. Try to deny as much farm as possible (unless you're against someone who counterpicked you AND has experience on that champion, in that case try to farm under tower and get 6 soon). At 6, you can go for an all-in. If you want to carry as darius, you really need to get ahead early, and most of the time a farm lead won't be enough if other lanes on your team are losing. At 6, you can go for shorter trades to harrass the enemy while staying healthy yourself (care for your mana tho, always keep enough up for a full rotation. Another tip: try to monitor the remaining duration of your passive, and try to refresh it. The more stacks on someone, the more pressured they are, and this also refreshes your bleeding damage which will stack up quite nicely), and if you're convident enough you can try to bait a gank, or just keep denying farm and create a lead like this. If the enemy plays too safe even though he's missing out on a lot of cs, plan a dive with your jungler. If you got early kills, just pressure top as much as possible. Your roams aren't that strong because of your lack of gap-closing and CC, so splitting will be your best option as you can quite easily 1v2 or even 1v3 depending on how ahead you are. Taking ghost can be better than tp, because most of the time in lower elo people only use tp to get back to lane, while ghost can help you with 1v2's or escaping ganks etc., as well as teamfighting. In teamfights: don't run in, you want to wait for someone to misposition so you can E him, or for someone else to lock him down so you can get your reset. Once you get your reset, the teamfight will become very easy to win, but splitpushing is still the most reliable way of carrying a game with darius. Pay a lot of attention to the map and get vision.
