Why?

The reason for Hybrid Ryze becoming op in this new season is the new items. Manamune turns max mana into ad which opens up a whole new mana focused hybrid ryze build which will leave your opponents dead and confused.

Ryze mid is uncounterable when played right.
Ryze is amazing at freezing the lane wherever he wants and then when hes ready to push, he ults and boom wave gone, ult back in 20 seconds.
So the secret is, you need to freeze the lane at that sweet spot, near your tower. Not to close that there's a chance for tower hits, and not to far that you can get harassed by enemy without them sacrificing themselves should a gank come.
You get all the farm, and become a boss late game.
Its that simple. if you do this, you dont need to worry about being ganked for a while and 90% of the time the enemy will get frustrated and try to harass you anyway, leading to a gank kill, or even you dodging there skill shot and zoning them easily till it comes off cooldown again.
At lower elo, they will even let you get off your Q W E Q combo which takes off half there life.

This is important. if they are low enough, FLASH IN!!! Q R E Q W Q and ignite somewhere in the middle!
if ur afraid he might escape no prob, start with W then Q R E Q ignite. You kill with ryze because they are frutrated and don't realise you kill so easily. true story. If you can lane well with ryze, it doesnt matter if you build my way or go ap or traditional ap mana, you will be one scary a hole mid late game.

Two notes on freezing the lane.
First, know it wont stay frozen forever and know how to deal with it. If they push you hard, you need to know the delicate art of farming under you tower so that when the next wave comes, its back in the sweet spot. q w and e help tons and you shouldnt miss anything. It gets a bit trickier if the enemy is cocky and you have to dodge skill shots while doing this. if he does this, PING YOUR JUNGLER!! easy ****ing kill!! you flash and freeze him, get off your combo, he gets off his. if you need to, your ult and/or ghost if you have it make catching him easy and finishing him easy.
If you do miscalculate and your lane is pushing, now worries, if you have wards, and can dodge the skill shots, push to his tower and then either roam or farm jungle. if you have no wards (get them) or cant dodge skill shots, roam or farm jungle till wave is back where you like it.

It's that simple.

You don't need wards cause your amazing at freezing the lane and have no fear safe by your turret, farming to your hearts content.
GO BUY WARDS!

not for you, for your team. while you freeze the lane, your enemy will be roaming and getting kills unless other lanes are forewarned well. wards and MIA's will do that.

If your counter is roaming, Punish them!!
Push the wave so they lose cs, follow them, or push the wave then follow them depending on the situation. BUT ALWAYS PUNISH THEM FOR LEAVING YOU ALONE!

and that is the laning phase.
To be a good Ryze, you should know your enemy well to dodge and to know when to kill.

I'm sorry i wont be much help here. It depends to much on your team comp, how fed you are and your unique play style.

I like to be very aggressive and be at the forefront in mid game and be an ap carry at the back late game.
but its all very very situational. Just remember, your not a squishy carry and your not a tank. your a life stealing bomb. The more they are grouped up, the more damage you do and life you steal but the quicker you can get cc'd and or burst down before you spellvamp to full hp again.
And yes, your ult is amazing you will get life very fast with it especially with a nice 20% extra spellvamp from an item.

well, im sleepy so im done for now, but in the future, i will be adding alternative build routes, laning play styles and ability explanations with more details on the combos. this is my first guide, so feel free to upvote and motivate me to do more. if i can figure out how to make a comment section, i will.