I am a 0.8M mastery who loves to play different styles. Those are what I have been trying to use in games, which turns out good results. So I am trying to share with all of you my build. Hopefully, it helps though my S11 didn't hit a higher ranking. But my other account hit diamond 1 in the previous season.

Ryze has changed into various positions than before. Tanky bruiser mage/ battlemage/ burst mage(Tho riot lower his dmg). Also, we have more choices on his items build.

runes work super-good for me while vs mages like leblanc/xerath/lux ; works good vs melee champs like / / / / .

Spell Guide:
Opening:
1, Lvl 1, Starting with Flex for range champs, with immobility one. also higher dmg than E, another important thing is always to think about trading with , if you can force your opponent out of his exp range, that's definitely the best thing you want to see. Sometimes lvl 2 with flex for harassment without taking minions dmg. But mostly flex is the better option. well-use your flex for the push. At lvl 3, uses flex for full pushing.
2, flex for trade.

Mid-game: (Most complicated part imo)
1, Don't forget to help your jg with scuttles. Usually, there's the chance to meet their jg too. Remember saving some mana for that.
2, Try to take a gold and exp lead and push the wave then back.
3, Always think of base when you have low mana, keep your tempo.
4, Push or Freeze wave to abuse your exp lead
, Ryze is a great split pusher, Always think about when to push. feel safe if you have your on. It's the best way to escape from ganking. He can do tons of pressure on push. So you have to connect with your team to group mid or another side lane. IMPORTANT: Group push doesn't mean you have to fight, they are buying time.
for you to do the shove. Keep your opponent busy if you can. Re-join your group if someone is coming to defend, that's the best time to join your team, and prepare for 5v4 fight.

Late game: You have to think about the priority target to root. sometimes a good root will change the game. Remember, Ryze is a battle mage, not a frontier. Your position is always the first thing you have to take care of.

Tactics:
1, Well-use yourFlex Prison on minions, freeze the wave. If your opponent is going to take cs, Add another Flex. If he has Flex , the minions to spread dmg, keep him away from getting gold.
2, As a mid-laner, I would recommend putting your first ward at bush or at the interchange of river and their jg at 2:20. So you could prevent their lvl3 jg from ganking mid.
3, Ryze takes advantage on shoving and taking lead at exp. But he has some shortage: Immobility, easier to get ganked. So always think about where their jg at, if you have no clue. putting wards are important before you start to push. I have seen a lot of Ryze players with good shoving skills but less map awareness. Improving your map awareness will make you do better in games.