is there any1 here who plays dota ? ... ever wondered why they nerfed bottle into oblivion and its still the most used item more or less ? , to regen mana and get into combat again is its biggest benefit , get 2 steps ahead of the person chasing you , pop it 5 3 secs later they turn , 6 secs later they die , its as easy as that.
and so much staying power you never need to go back again.
and a pushing tool aswell , charge the tower until you get low on hp , heart up get back again.
also oak with shield , erebus with bat form , activating it after a stun/freeze will net you about 600-900 mana and hp aswell.
all this for 4250 , only hero ive tried to not use it on is rook as he only needs regen/hp items but alas i wished i had it anyways