I think spoken magic is a great idea, kind of like the mechanic in Project Gorgon where certain powerful words can be discovered and then when they are said in chat they are activated.
In Project Gorgon these words once activated can never be used again. But instead I think that they should be syllables that refer to elements, as suggested by CorvusSolus.
Then players could sit at home chanting random combinations, attempting to discover spells. Some combinations would be harmful to the player and could potentially kill the chanter. So discovering spells would be at the potential cost of life or limb. Once discovered though, spells could be inscribed and sold or taught to players of a particular order.
In order to offset the danger in researching spells. Perhaps chanting spells successfully could make the player more resistant to failed spells in the future. Meaning, that it would almost never be worth it to study magic without scrolls (finding runes with inscribed spells in world) or an older player guide. Though players could always attempt to explore magic if they were willing to take great risks.
In order to prevent spells from simply all being uploaded to a wiki. Perhaps spells could expire over a certain number of uses or period of time. Or perhaps any spell could backfire, making magic dangerous in general unless wearing certain items or being in the presence of a magical guide or experienced magic player.