User blog comment:Leyrann/Why Chalice of Harmony is OP/@comment-86.8.9.144-20120827124900/@comment-4834593-20120827141833

Philo Stone gives 8 MP5, nearly always lower than Chalice gives (you need about 97% or less mana to get more from Chalice than from Philo Stone), and does not increase when you have less mana. If I have 0 mana in a mana pool of 500, Philo Stone gives 8 mana over 5 seconds, where Chalice gives 15 plus an amount equal to your passive (it also increases passive mana regen).

I agree Jayce might have been a bad example. However, Jax is a better one. After a few times QEW plus one or two autoattacks you will be oom, before you have been able to kill your enemy.

Also notice that, even if you sell Philo Stone, it only pays itself back after 13 minutes and 20 seconds. Chalice never takes that long, plus it can give you defense against AP tops (might you face one), and against mids, some junglers, and supports once the laning phase is over, while Philo Stone becomes near useless then.

You might also pick it on AP tops like Malphite and Swain (if played top) to buid into Athene's later on, because it's one of the most powerful items in the game.

Another advancement it gives, is that you NEVER have to go back because you are low on mana. I sometimes notice myself having about 3k gold when I go to base with bruisers, because I got huge health regen from Warmogs and huge mana regen from Chalice.