2 to 15 people sit with you in a conference room. They ask you questions in Russian, then English and German, since the last two are used for the job in the position and the first one is considered to be your mother tongue if you apply in Saint-Petersburg, Russia.
They ask typical stuff first about your background and why you decided to apply for this exact position, what you like about testing etc. Then they provide you with logical and applicable tasks. Logical ones are different and believed to test your mind's flexibility. They are abstract. Depending on the number of people in the room, however, it can be difficult to concentrate on the process of finding a solution so I really recommend to think out loud even if you are normally not inclined to do that. It helps you to not lose track of thoughts, to show the interviewers your way of thinking and to remember where you left off when someone interrupts you with another question. Practical tasks involve demonstration of knowledge in specific software/technologies needed for work. But you're not given a laptop or a pc. You just have to write commands/code on a piece of paper so be ready for that. I was trying to solve some tasks in SQL and XML on the paper. The same goes for emulation of filling some fields in a bug tracking software. You just write peconditions, actions and result on paper.
Since interviewers come from different projects, they will tell about them at the end of the interview and will listen to your questions. Just because interviews are poorly organised in terms of time, interviewers may leave whenever they want and they do. This does not mean they have no interest in you. At least it shouldn't. But it's an act of disrespect to an interviewee and perfectly tells about human nature. Many don't apologize for leaving early so you may assume they are not interested in hiring you at all.
TL;DR: It's a basic no pressure interview. The only confusing things may be the number of interviewers (up to 15 at once to my knowledge) and them leaving the room midway without saying a word.