How do I print core block or views block in node.html.twig? I'm pretty new to D8, so this might be basic stuff, but I can't find any tutorial how to do it.

In Drupal 7 this is the code that outputs core block in node.tpl.php:

&lt;?php $block = module_invoke('block', 'block_view', '10'); print render($block['content']); ?&gt;


This works for Views:

&lt;?php print views_embed_view('viewname','block_10'); ?&gt;


How do I achieve this in Drupal 8?
In Drupal 8, you don't need (and should not) render in PHP. The rendering is done as late as possible in Twig.

So put the build array of your view in a variable.

function mytheme_preprocess_node(&amp;$variables) {
  $variables['view1'] = views_embed_view('view1', 'block_news');
}


And then render it with {{ view1 }}.

Twig will handle the necessary rendering for all kind of render arrays that are possible in Drupal.

You can use the same for a block. (See the comment from Ivan Jaros.)

$variables['block1'] = entity_load('block', $id)-&gt;getPlugin()-&gt;build(); 


The build() method gives you the build array of the entity and you can use {{ block1 }}.