The new support item quests shouldnt be only depedant on gold-gains.

Instead, they should keep track on what a support actually DOES:

-> a champion who buys Spellthieves should be an enchanter. So the quest should be about damage prevented through shielding or healing done. This prevents it being abused by mages. And if you really WANT mages botlane, you could also add a "enemies cced" into there...

-> a champion who buys Targons is already forced to be in a duo lane, so the quest might sty the same. HOWEVER, what might be better: instead of a shield change the active to a link that transfers % of damage taken from the allied target to the user. You might even make it a second quest depedant on the amount of damage you have prevented on your carry.

-> and finally coin... not sure who the this item is intended for anyways. If you are tanky with cc you go targons. If you are a mage with utility spells, you go spellthieves. If you have neither tanky cc or utility and you are neither the carry or the jungler coming for a gank... what the hell are you even doing on botlane? I mean, yes I remember double melee kill-lanes, but those run double-targons mostly with much greater success. You might as well remove the coin-line and put that active on a new item or something...