54.210.14.0 coming from the Amazon ranges.

Personally, I block the 54.210.0.0/15 range along with most of the 54.0.0.0/8 but if you wish to block only that bot, you can look at UA blocking.

Edited to add -
I had not heard of Clickagy, a lookup tells me they are a

data intelligence company that works with leading marketers to anonymously identify and segment audiences based on their real-time digital behaviors.

..also specialize in AI, 3rd party data to provide behavioral B2B intent data.

:: obligatory detour to raw logs ::
 
Nope, never set eyes on ’em. That suggests they're targeted in some way. Not in the sense of You asked for it, or You must’ve done something to make them mad ... but some aspect of the site causes them to show up.
 
:: uneasily wondering how long ago this subforum’s name was changed--to say nothing of the wholesale restructuring of categories--and I never noticed ::

Well our site's been around for over 25yrs so theres no telling where they found it from. I blocked them in my .htaccess file so they'll get the good ole 403. I used to block all the Amazon server farms since there was so many site scrapers on there, but we recently moved our server and those blocks didn't transfer over... So I'm spending a lot of time going through the logs again. Usually I just use Web Log Explorer, but is there a better one that would help me find the naught bots?

If you are running advertising on your site, your site is probably being visited by bots associated with the ad networks, which check where the ads are being placed. Some are in near-real-time, others are within 24-48 hours.

I tested this out by creating a dummy page, putting ads on it, and visiting it. I should be the only IP to hit the page, right? Wrong. About 4-6 other IPs came in and visited the page, all bots, and some of them not identifying themselves as such.

Never saw much of anything from AWS worth embracing. Ad networks (if I can identify them) are tossed to the curb. THIS IS ONE OPINION not held by very many. Always did my own ad sales with local, regional and national clients, so the competition was not invited. :)

Still, these new folks doing the "ad" thing are becoming more invasive as the months and years pass! Most times, if not impacting my site(s) I let them live. Otherwise, the 403.