Analysis of Sightstone(s) cost vs benefit. (Shut up about SS wasting inventory space)
TL;DR sight stones are massively gold efficient for supports
What's their cost and stats?
-800G
-150 hp
-3 wards each time you back
50% gold efficiency without counting unique passive. 400g value
Counting unique passive, assuming that wards are 75g(the price before they were removed), all you need is to place 6 wards before it starts being positively cost efficient.
-2200G
-500hp
-200% hp regeneration
-spoils of war
-4 wards each time you back
87.88% gold efficiency without the passives. 1933.33g value
In order to compensate for the remaining 266.67 gold you would need to wait 22 minutes and 14 seconds, place 4 wards, or kill approximately 11 melee minions.
-1900
-200hp
-100%base hp regen
-100%base mana regen
-10% CDR
-favor passive
-4 wards each time you back
84.21% gold efficiency without the passives. 1600g value
In order to make up the extra 300 g, you would need to place 4 wards, get the gold from 60 minion deaths, or (counting for the fact that one minion deaths heals you for as much as 26.67g of health potions) only 10 minion deaths.
-2200g
-25 ap
-200 hp
-100% base mana regen
-10% CDR
-tribute passive
-4 wards each time you back
83.81% gold efficiency without the poassives. 1843.75g value
In order to make up the extra 356.25 g you would need to place 5 wards, wait just under 30 minutes, or proc tribute 24 times.
-1600 gold
-500hp
-4 wards each time you back
83.33% gold efficient. 1333.33 g value
in order to make up the extra 266.67 g you would need to place 4 wards.
These items are not gold inefficient unless you go out of your way to not use the passive. They can technically be infinitely valuable in a game but more realistically they can be around 200-300% gold efficient if you place enough wards and use the passives effectively. The gold generation passives can pay for over half of the item just by themselves. I greatly stress this next point.
Sight stones are not built in other roles in the game because the majority of their use comes from the gold gen passive along with the wards. The different passives are useless if you are the one last hitting CS.(With the exception of ruby sight stone being kinda worthless in comparison to other SS items.)
Technically you can build a support item to get the warding done yourself. The barriers to this are that you waste an item slot on the incredibly low stat
or waste a gold gen passive on nothing. Most people just cross their fingers and hope the support is competent enough to cover vision by them self.
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which also offers unique utility through an active, yet it is allowed to have stats that make it worth picking up. These items are desirable both for it's active and it's stats.
to crap all over your "Support only item"-argument, LOL.
would all be able to carry ward charges.