The "A" key is arguably the most underutilized prime real estate on the keyboard for Dota 2. In the default setting, "A" is used for Attack Move. While useful, Attack Move is arguably less critical to have on a split-second reflex key compared to an active item like Glimmer Cape or Force Staff.
: Mapping "Inventory A" to a side thumb button on your mouse for instant reactions. inventory a dota hotkey
As of the 7.xx patches, Dota 2 has a dedicated (Slot 6, far right). This is typically bound to V or N by default. However, Neutral items are often game-changing actives (e.g., Trusty Shovel, Flicker, Timeless Relic). The "A" key is arguably the most underutilized
With Normal Cast: Press C -> Click enemy. (Two actions) With Quick Cast: Hover mouse over enemy -> Press C . (One action) : Mapping "Inventory A" to a side thumb