Philosopher's Stone Craze

Philosopher's Stones are becoming much more popular in play after the addition of the new Tenacity upgrade which provides 25 Tenacity and reasonable HP/MP regeneration.

I decided to take a closer look at the possible impact of this item, especially after Heart of Gold lost some of it's usefulness with the Armor component removed.

The question is: Is the philosopher's stone a useful item branch?


Arguing if the PS is useful is redundant, it's used by many people early game but is it worth the slot later on?


First, let's see how it's built:
435 gold for a Regrowth Pendant
180 gold for a Faerie Charm


This gives you 15HP/5s and 3MP/5s respectively. 


The upgrade to Philosopher's Stone is 185 gold. For 185 gold and those two items, you get:
+7.5 HP/5s
+7 MP/5s
+5 Gold/10s


You are given a Meki Pendant, a Rejuvenation Bead and 5g/10s for 185 gold. It's an amazing deal, but now that you bought it early game, what can you do with it?


Well..


10 Minutes: You have gained 300 gold from your Philosopher's Stone. Your potential regeneration is 2700 HP and 1200 MP.


20 Minutes: You have gained 600 gold from your Philosopher's Stone. Your potential regeneration is 5400 HP and 2400 MP. Your PS has nearly paid for itself and selling it will set you back 200g.


30 Minutes: You have gained 900 gold from your Philosopher's Stone. Your potential regeneration is 8100 HP and 3600 MP. Your PS has now paid for itself and selling it will net you a 100g profit.


40 Minutes: You have gained 1200 gold from your Philosopher's Stone. Your potential regeneration is 10800 HP and 4800 MP. Your PS has now more than paid for itself and selling it will net you a 400g profit.


Those are big numbers from a 800g item, but is it worth hanging on to?


Consider an entire team with a Philosopher's Stone. Although it's not the smartest choice for every character (usually it's best to get it on tanks/support/anyone who shouldn't farm a lot and would benefit the most from the regen tenacity upgrade) you do get some shocking numbers.


In half an hour your team is 4500g ahead of the enemy team, has regenerated 40500 HP worth of lane staying power and has about 18000 MP worth of mana on the enemy team.


These are, of course, hard to quantify. You can't count all the times you're at full MP or HP and you aren't regenerating, but the gold keeps coming in.


What's the verdict?


The Philosopher's Stone is definitely worth the money and is one of the best early-game items. Hanging on to it up to and past 30 minutes is only recommended if you don't need the slot, and support characters should upgrade to the Tenacity item when the extra income is not needed, as they will benefit more from this after the laning phase. It's also a good item if you are being pushed to your tower or zoned and need to stay competitive gold-wise.


Philosopher's Stone
Pros:

• Great lane survivability
• Cheap
• Pays for itself in time
• Well-rounded item (suitable on most champions)

Cons:

• Only two upgrade routes
• Will most likely be sold after early-mid game (doesn't upgrade to late-game items)
• To get the full effect you need it very early, buying it after 10 minutes means you need to hang onto it to 40 minutes to pay it off.
• No benefit in team fights