In uBlock there is already the "Block Element" tool, but there is one feature of Adguard that makes me switch to it constantly to write new filters, which is called "Block similar elements".

As an example, on Inoreader.com, uBlock blocks ads, but leaves empty spaces between feed items (the cosmetic filters don't work there).

Using uBlock, I select the empty space, and it returns the element ###leaderboard_ad-564435f7bb14f to block. The problem with this approach is that 564435f7bb14f here is just a random string, which changes every time I visit Inoreader.

To block ads like this effectively, I have to activate Adguard, open the "Block Element" dialog, select that element, which will return ###leaderboard_ad-564435f7bb14f too. But then I click on "Advanced settings" and then "Block similar elements", which gives me inoreader.com##.block_article_ad, .mobile_leaderboard_ad, .ad_size_mobile_leaderboard, .sinner instead. I have used this rule in uBlock and it always works!

I have seen some very annoying ads on some other websites which also use that random string approach, and I can only write the rules easily for them with Adguard, and then I import them to uBlock.