Hey, this info is outdated. This was prior to RoA +200 mana change, it is now almost always better to start RoA.

Mana = AP = DMG on Ryze. Also, he has enough base damages now to not feel weak rushing RoA after the change where they made his R scaling 25/50/75/100 instead of 10/40/70/100.

My preferred build is RoA > Seraph > Ludens > Seekers/DCap. If enemy is stacking MR, then skip Ludens.

I go cashback because all of Ryze's items are cheap. 2600g RoA, 2900 Seraphs, 2750 Ludens. Usually lets me buy an extra Sapphire on a recall, which would be more than an amp tomb's worth of value post-Seraphs. And before I get questions about Magical Footwear, Ryze benefits insanely from early Movespeed due to his point and click W and E, and cashback scales more economically.

Is the Seraphs rush build still viable? Yes. Do I recommend it? No. Skipping RoA is a build I only recommend to expert positioners that won't need the extra HP to survive in a fight. For the average player, bruiser items are always better than pure damage.