Quick cast

Smart cast is a characteristic of some abilities in League of Legends. All champion abilities can be set to smart cast by editing the preferences for hotkeys and commands.

Gameplay
Smart cast automatically casts the selected ability at (or towards) the current mouse cursor position as if you had first pressed the ability button and then left-clicked at the target position. Smart cast works for self-buff abilities, targeted abilities, ground-targeted abilities and skillshots. Smart casting a support buff ability (an ability that can be cast on self e.g. a shield or an heal) when the cursor is on an invalid target will self-cast the ability instead. Note that you can use self-casting to self-cast support buff abilities regardless of cursor location. Using smart cast can be invaluable because it reduces the time delay between activating and casting by cutting the user input in half; activate vs activate and click.

Remember that smart casting means you don't get the targeting graphic, which can make it harder to accurately aim skillshots. They will fire instantly, instead of showing the skillshot for fine tuning the shot. However, there is an option to turn range indicators on, which will show the targeting graphic while the ability key is depressed. This can also be helpful because the ability can then be canceled by right-clicking.

List of abilities that smart cast
The following abilities automatically employ smart cast:

Smart cast for special skill shots
Complex skill shots, such as vector skill shots like and, and  can be smart cast by holding down the smart cast hotkey to mark the beginning of the line, and releasing the hotkey to cast.

Tapping the smart cast key normally will result in a straight forward skill shot fired in the same direction as the champion.

This method of smart cast was introduced in V1.0.0.129 to allow vector skill shots like to be used with smart cast.

Smart casting glitch
There is a glitch that may cause to only fire at the targeted point instead of hitting in a line when the regular smart cast method is applied. This glitch does not appear when vector smart cast is used instead.