The Ksillsombi.com website doesn't contain anything useful for its visitors. Instead, it tries to take advantage of them through misleading and manipulative social engineering tactics. More specifically, the site tries to hide the fact that it wants users to subscribe to its push notification services unknowingly, by implying that clicking the 'Allow' button is connected to some completely unrelated activity.
This particular tactic has been quite popular among certain circles of unscrupulous people and thousand upon thousand of virtually identical rogue websites have been flooding the Internet. These sites try to create the impression that by clicking the 'Allow' button users will be completing a CAPTCHA check, gain access to a video, or that a file will become ready for download. Ksillsombi.com builds on top of that by also implying that its visitors have won a rather lucrative prize, such as an 'iPhone X.' Again, to receive this non-existent reward, users are directed towards clicking 'Allow.'
The last part of the tactic involves abusing the received browser permissions to run an intrusive ad campaign. Ksillsombi.com may deliver numerous unwanted advertisements to the user's device via the affected browser. The advertisements could be promoting shady software products, PUPs (Potentially Unwanted Programs), adware, browser hijackers, other scam websites, etc.
If the frequency of encountering pages such as Ksillsombi.com is far too high to be completely accidental, it may be a sign that a PUP has already managed to infiltrate the user's device. That is why it is recommended to use a professional security solution to routinely scan your computer or device for any suspicious applications that may have appeared on it suddenly.