Ryze in my opinion is one of my favorite champions to play, I never played him before his revamp so I don't know what he was like before, but as of now he is awesome. This build is what I use every game I play as him and I always do exceptionally well, more kills than deaths and even more assists than kills. You can take some damage and deal a ton of it, and you will be able to 1v1 pretty much any champ easily.

Pros
+Able to take damage
+A ton of burst damage
+Good CC
+Nice AOE
Cons
-After initial burst it dies down a little
-You will get focused
-Snare instead of a stun

To be honest I'm not really sure what to do for runes for him, I'm open to suggestions so if you think something else is better suited, be sure to leave a comment saying so.

greater quintessence of knowledge - Just mana per level runes, each one gives ~ 75 at level 18 so you will be getting ~225 mana at level 18.
greater mark of knowledge - Mana per level, about ~21 per level so roughly 190 at level 18.
- cdr per level, this will give you a nice amount of cdr at level 18 which will help boost your damage.
greater seal of knowledge - Mana per level, ~21 per level so another 190 at 18.

Totals
3.45% cdr at 1
11% cdr at 18 (+ another 10% for max )
33.57 mana at 1
604.26 mana at 18

- 3.36 extra damage at level 1, 60.4 extra damage at level 18.
- 1.67 extra damage at level 1, 30.2 extra damage at level 18.
- mana has no effect on it.
- mana has no effect on it.

- Flat mana, each one giving ~38 mana for a total of ~114
- Flat mana, roughly 6 mana so about ~54 mana.
- cdr per level, same as first build
- Flat mana, about 7 mana which will grant ~63 mana.

Totals
3.45% cdr at 1
11% cdr at 18 (+ another 10% for max )
227.7 mana at 1
227.7 mana at 18

- 22.8 extra damage throughout
- 11.4 extra damage thoughout
- no effect
- no effect

As you can see, this one has a stronger early game, but a weaker late game. It's all up to personal preference though.

For masteries I just went with something general because ryze doesn't benefit too much from going 21 into one.

If you feel something is better suited, go for it because they don't really make too much of a difference.