User blog comment:Willbachbakal/(Item Concept) Spell-Based Sustain/@comment-973379-20141108120035

"Ryze's Desperate Power no longer gives spell vamp and instead allows him to heal for 5 / 6.5 / 8% of the damage he deals through abilities. This is pretty much the exact amount of healing Ryze actually gets when he activates his ult, give or take a fraction of a percentage point. His spell vamp and spell AoE-ification sort of work against each other, so the stats listed are a lot less impressive than they look"

NO. Ryze's spells when he ult are still single-target spells with some AOE, that calculated(in terms of spell wamp and rilay) separately. So if primary target take 1000, secondary take 500 and you have 20% spellvamp you get 1000*20%+500*20%*0.33=233 hp.