Bratislava is well known for party, and if you come looking for it, you have come to heaven, there are enough clubs here for you not to repeat one during the erasmus, so... that's a lot!
It's pretty common that you need to pay for going in, around 2-5€ and even 10 if you come after 23:00, I recommend to go before 23:00, get the entrance and go to you pre-party place until you are ready. Drinks can be from3 to 5 euro, but beer usually doesn't cost more than 3€ for half a litre, so it's a good option. As I said in the money management guide, if you have a flask, you can sneak it inside and have some drinks for free!
As I did in the Bratislava Cheap guide, I will talk about the club itself, not because of the music, because it changes every night, for example one night can be DnB and the next one Indie party, with totally different atmosphere.
There are many other clubs! They will be added soon.
This is the definitive guide for a Erasmus or a Student in Bratislava, all info I know about the city will appear here