It turns out you can't smartcast Hextech Gunblade's active ability after the Hecarim Patch. To clarify, you can set it to smartcast, but you'll still have to activate the ability, then click on a target, rather than activate the ability, and move your cursor over a target.
Are there any items with active abilities that can no longer be smartcast? Or is this just a bug?
Best Answer
It's possible to smartcast all items with an active ability (including wards).
As Andrew already explained, you can go into the "Kebybinding," go to the category "Item Inventory," and from there you can set "Smart Cast Items 1-6" to your preferred key (I would suggest taking the numbers 1-6).
List of Items that currently have an active targeting ability (excluding consumables):
Note: All items with an active ability that don't require you to choose a target (e.g. Runduin's Omen) are used by simply pressing the corresponding button to the item slot (no matter if you use Item smart casts or not).