This is honestly confusing me. Why did we put it in an AD item and a tank item? I get that you can only use it once, but its one of, if not the most, powerful actives in the game. Shouldn't this only build into Zhonyas? This just really makes absolutely zero sense to me.
Tenth Leper1 votesThey are all limited uptime self defense items.
They added a rune which reduced their cooldowns, but to make sure it was an attractive rune they added a component with it which reduced the cost of the items in question.
If they hadn't done this they would have needed a single use version of each of the other items too, and some way for the runes to know which of the items you were planning to get so it could get you the proper component.
