How to set where user is redirected to after logging in at wp-login?

Filter 'login_redirect'.

Sample code, not tested:

add_filter( 'wp_login', 'wpse_78150_login_redirect' );

function wpse_78150_login_redirect( $url )
{
    # uncomment the next line for debugging
    # var_dump( wp_get_current_user() ); exit;

    if ( ! current_user_can( 'custom_role' ) )
        return $url;

    return admin_url();
}