A single purchase of this item could easily flip a game around changing unwinnable fights into one sided clashes. BKB is an item often ignored by many, even by high level players, but through good consideration and good timing, BKB could be the item that wins you a game. The cost of the item isn’t really high considering what ir provides for some heroes, a 10 second magic immunity period is more than enough to fight against a heavily spell oriented lineup.
With heroes like Invoker, Tinker and Ember on the rise, BKB make sit easier to deal with them. Invoker has it better, but versus Tinker and Ember, often times BKB and a dagger would be almost a perfect way to stop them- especially with stronger heroes such as Pangolier, Templar Assasin etc.
Most players often get the item too late, or too early, when it is not needed. However both are better than those who choose not to get it at all. Often times we see games being throw just cause the carry doesn’t get a bkb. Definitely one of the most important items in some games!