You Do Need power plug adapter while traveling from Czech Republic to Brunei.

Here is Why You Need An Adapter

The outlet and plug type used in Brunei is G and in Czech Republic are C and E. This is how they look like.

Czech Republic

In Czech Republic, outlets of type C and E are in use.

Type C

Type E

Brunei

In Brunei, outlets of type G are in use.

Type G