How did they determine which teams were going to IEM Katowice?

There were four IEM events that were won by Team WE, Yoe Flash Wolves, Cloud 9, and Gambit Gaming. Then, the #1 seeds after five weeks I believe in the NA/EU LCS and LCK were invited, which brought in TSM, SK Gaming, and GE Tigers. Then, to round it off, CJ Entus was invited because they are the #2 team in the LCK and they wanted to have a second from there since there were two from the other main regions competing, outside of China which had their schedule already set in stone and could not send any other teams.

So that's how we're at where we are.

C9 won an IEM event

Gmb - won IEM cologne

SK - were first in the LCS at the time the qualifications were decided

TSM - see sk

C9 - won IEM San Jose

WE - won IEM Shenzhen

YOE Wolves - Intel Extreme Masters Taipei

GE Tigers - First in LCK

CJ Entus - 2nd in LCK

It's not going by the best in the regions, it was the teams who won the respective IEMs, and after that it was the 1st place teams in their respective region at the qualification deadline. They supposedly picked two spots from LCK so they could have regional balance.