I'm sorry, but Muramana is ridiculous on champions like Ryze
 

It increased his overall DPS by 200+ PER spell.
His burst sums up to around a full Veigar combo, while still remaining tanky.

A Ryze can technically have this item and ROA, and 1 shot almost anybody.

Hadn't you hear? Riot is in love with their mages (and supports now, apparently) and is only interested in a few concessionary bones for ADs...bruiser love is nowhere to be found.

Love with supports? Your kidding right? This is the first patch that they actually paided attention to Support needs, but they took out a major source of their income. Actually 2.

Pickpocket, passive gold increase, the existence GP10 items that continue giving gold while also providing insane benefits (kage's last breath), sight stone, better starting income, a free mini-ward and mini mana+HP potion to start with, not mention way less boot dependent for a longer time more than makes up for the gold mastery supports lost.

I would think the shield on Seraph's would be better, but I haven't had the chance to charge up an AA.

While this is fun right now, its sure to be nerfed. They will probably make it "single target physical damage spells" or make it melee only or somethign.

Or they'll just nerf Ryze.

Melee only wouldn't really be fair to the rare cases where a ranged would use it, such as Urgot or Ult-Spam-Poke Kog or something.

Meanwhile, can't be Physical only because Yorick is the largest user of Manamune and one of his two single target spells deals magic damage so it would only be used on his Q.

And here I thought Muramana would be Pantheon's big break...

Physical is probably the best suggestion, for unique cases like Yorick, just ask for that individual champion to be changed