To expand upon the countering of airborne effects, consider that the effects are made up of two components: a movement modifier (called a "move block" by Riot, referring to a chunk of code) and a stun (which is responsible for the disabling attacking and casting). As a general rule, the most recent move block will over-rule any previous move blocks, which is how Alistars20pxHeadbutt and 20pxPulverize combo functions. This rule also extends to all beneficial movement modifiers, such as dashes and blinks, which is why 20pxRocket Grab and 20pxRocket Jump will over-rule each other depending on their order of activation. Most beneficial movement modifiers do not prevent the activation of abilities, allowing Tristana to still activate abilities during 20pxRocket Jump but not during 20pxRocket Grab).
Through the use of cleansing effects or tenacity, players can remove the stun and subsequently activate abilities such as 20pxFlash or champion-specific dashes to break the airborne's move block.
In some instances, the stun duration is longer than the move block (e.g. Sions20pxUnstoppable Onslaught), but in most cases they are the same duration. There have been cases in the past where the stun duration was shorter, but this usually lead to bug-like interactions and was later "fixed" (e.g. Azirs20pxEmperor's Divide did not apply any stun at all in the initial charge on the ability, which allowed his enemies to use Flash/dash to supersede the charge's knockback and get over the wall).
20pxThornmail's passive returns 30% of all physical damage back to the attacker as magic damage before the damage is reduced by any effect, including blind. So it still applies if the target is blinded.
Blinded enemies will only miss if they attack while blinded; ranged units still hit if the projectile fires before the blind.
An argument can be made that Nearsight is a debuff, rather than a form of crowd control, due to it not being affected by crowd control reduction nor immunity, as well as being resistant to cleanse effects. However, as the effect disables the use of some abilities and all but one source is a persistent effect (i.e. they cannot be removed or reduced anyway), it is being listed here.