Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
My build is designed for solo mid lane play. You will be the carry of the game for your team with this build. You need to start off with Doran's shield for an early game boost on your already impressive tanking stats. Your mission with this build is to focus on killing creeps. You will win the middle lane by pushing, alone. Spamming your siphon skill is your most damaging attack early on and is effective throughout the game. Watch out for players with silences or players that inflict grievous wounds. Players with a silence cut away your shield and halve your effectiveness in a lane. Players that cause wounds hurt your healing rate over time. Katarina can be very dangerous once she gets her ultimate, be wary. Your ultimate is important for getting health back during a battle, when going for a kill place your ultimate and ignite on your target and do as much damage as possible while it runs away. That should score you a quick first blood if the other lanes are slow, early on.
The reasons for my masteries is to focus on taking reduced damage while increasing my potential magic damage.
Your skill sequence is important because you will focus on making your siphon and creeping death skills maxed as early as possible. The increased damage from mace of spades is inconsequential, because most of the damage will be done by the Sunfire Capes and your other two skills.
Your rune build will increase your health to ~900 giving you plenty of breathing room when facing off against level 1 opponents. The build also focuses on cool down reduction runes, but those could be replaced by the health Glyphs, instead.
The only items that are important for winning the game are as follows; Doran's shield for early game domination, the boots of swiftness for catching up to every single player on the opposing team, and finally the dual Sunfire capes to take chunks of damage from whole enemy teams over time. Everything else on the list is just added to keep yourself alive or slow the other team down. Randuin's is very good for slowing fleeing enemies and it does give some health regen, but is quite useless other than those two purposes it serves.