Riot takes a very comprehensive approach to employee interviewing. As a design applicant, I was put through multiple design tests, an IQ and personality evaluation, and then two phone screens before being invited for an on-site interview. Initial tests and communications were handled by the hiring coordinator, though my applications had been read by senior personnel within the design department.
The on-site interview was entirely paid for by Riot (plane, taxi, parking, and hotel), and I was set up at a very comfortable hotel for the three days I was in Santa Monica (arrival day, interview day, and departure day). The on-site interview occurred on the second day, starting from 10 AM to 5 PM, where I participated in roughly seven one-hour interviews with various design and production personnel of varying positions. Each interview was geared towards evaluating me in separate areas, including general knowledge, design knowledge, culture fit, personability, and work ethic. By the end of the day, I believe the interviewers had a good understanding of who I was and what I could do.
It's worth noting that (to my knowledge), all significant hires will speak to senior personnel at some point in their interview. The design director took me and several other designers out to dinner that day, and a week later, I spoke on the phone with the CEO and President of the company (both were out of the country during my on-site interview; otherwise, they would've interviewed me on-site). This is a fairly unique privilege given how busy large game developers can be, but it shows how relatively "flat" the organization is when the highest ranking personnel take the time to close the deal on all their new hires.