HOL is not overpowered. For most games, its actually cheaper to just buy potions. Over the course of your average game, use potions instead of the HOL -- you'll find that you probably didn't use >10 potions (which is the cost of the HOL). Potions are cheaper, and let you buy other items at the same time. Early game advantages translating into late game advantage is the key to the game, and the by the time you've saved enough for the HOL, you were probably better off getting potions and items instead.
You aren't taking advantage of the power of HoL, especially on power heavy characters such as the QoT and Torch Bearer.
If you are simply using it to heal after a fight, your probably doing what it was intended for. It is literally the only mana item I purchase all match and constantly keep it on cooldown. I EASILY use it more than 10 times every match, more than 20.