You can use the Expertise: Magic skill to create and cast magical rituals. This advantage is often a back-up or secondary magical power for superhuman sorcerers, and may be the only form of magic available to some “dabbler” types.
Characters with the Ritualist advantage can perform magical rituals. They are similar to inventions: one-time powers requiring some time and effort to set up.
For rituals, substitute the Expertise: Magic skill for both the design and construction checks. The design portion of the ritual takes 4 hours per power point of the ritual’s cost (pouring over ancient scrolls and grimoires, drawing diagrams, casting horoscopes, meditating, consulting spirit-guides, and so forth). The performance of the actual ritual takes 10 minutes per point of the ritual’s cost. So a ritual costing 10 power points takes 40 hours to research and 100 minutes to perform. As with inventing, the ritual is good for one scene. Failing the research check means the ritual isn’t usable and three or more degrees of failure results in a mishap (at the GM’s discretion).
“Jury-rigging” a ritual has the same effects as for an invention. Spending a hero point allows the ritualist to skip the design check and perform the ritual in a number of rounds equal to its cost. An Expertise: Magic check against a DC equal of (15 + the ritual’s cost) is needed to successfully perform the ritual. Failure means the ritual does not work and the time and effort is wasted.
D20 Hero SRD Advantaged Article- http://www.d20herosrd.com/5-advantages/