Clairvoyance

Clairvoyance as a summoner spell doesn't really see much use, and the reason being because it simply doesn't bring enough to the table. With the improvements and additions of trinkets being able to provide reliable vision there is even less of an incentive to grab clairvoyance nowadays, especially considering blue trinket does its job better without taking up a summoner slot.

So my suggestion is, have clairvoyance provide true vision for a slightly longer duration, this way it is effectively a mixture of redtrinket and bluetrinket, and can be useful for checking on stealth champions from a distance like evelyn or even for clearing wards and fighting stealth champions. Alternatively, have its vision have a much wider radius, doubling or even tripling its radius, but without the true vision, and I think I'd personally prefer this usage.

I think that without these changes, nobody would even consider grabbing it, as it needs to provide some reason to grab it over a true damage DoT that reduces healing (ignite), an instant displacement blink (flash), preventing a target from escaping or even properly participating in a fight (exhaust), and a global teleport (teleport). Compared to those, having proper reliable vision of somewhere sounds plenty reasonable.

This could be used to reliably scout areas from a safe distance before claiming the territory yourself, to detect stragglers for fights, and pretty much useful for vision in general.