Coin-Line Gold Passive Rework Idea:
What I am going to suggest here is something of a hybrid of a slight passive element still, but most of the gold income will be moved into a very active role and get properly rewarded for doing so rather than the coin-line current passive gold income just for afking in the brush (this is a boring way to play for everyone and something we shouldn't encourage when playing as support, you are making the lane a 1v3 for your marksman rather than making it a proper 2v2 since you are stealing exp and doing nothing). Essentially think of something more akin to spell thief since mostly mages will be the ones getting this item, with more emphasis on shield and heal mages.
On that note, a slight stat change will be in order, like remove health regen and in replace you get shield and heal power (you can only get one gold item remember so it doesn't need to be an unique passive). The item will heal yourself whenever you expend a Coin, more on this in a bit, but even if you don't have a shield or heal in your kit (unlike Janna, Lulu, Soraka, Sona, Taric, Ivern, Alistar, etc.), the shield and heal power is not completely wasted (also there are items with shields and heals).
COIN TIER ONE [ANCIENT COIN]: +25% Base Mana Regen +5% Cooldown Reduction +2 gold per 10 seconds +Passive: Gather a Coin every 3 seconds, up to a maximum of 10. Each Coin expended grants 2 gold and restores 2(+5%AP) health. Minion executes lock you out of expending a Coin for 12 seconds. +Passive: Your heals, shields, or speed ups against allied champions expend 1 Coin. Basic attacks against enemy champions or structures expend 2 Coins (4 Coins for melee attacks). Abilities against enemy champions expend 4 Coins.
COIN TIER TWO [NOMAD'S MEDALLION]: +75% Base Mana Regen +5% Shield and Heal Power +10% Cooldown Reduction +2 gold per 10 seconds +Passive: Gather a Coin every 3 seconds, up to a maximum of 12. Each Coin expended grants 3 gold and restores 2(+5%AP) health. Minion executes lock you out of expending a Coin for 12 seconds. +Passive: Your heals, shields, or speed ups against allied champions expend 1 Coin. Basic attacks against enemy champions or structures expend 2 Coins (4 Coins for melee attacks). Abilities against enemy champions expend 4 Coins.
COIN TIER THREE [NOT ALL OF THE STATS FOR EYE OF THE OASIS AND TALISMAN OF ASCENSION]: +100% Base Mana Regen +15% Shield and Heal Power +10% Cooldown Reduction +2 gold per 10 seconds +Passive: Gather a Coin every 3 seconds, up to a maximum of 12. Each Coin expended grants 3 gold and restores 2(+5%AP) health. +Passive: Your heals, shields, or speed ups against allied champions expend 1 Coin. Basic attacks against enemy champions or structures expend 2 Coins (4 Coins for melee attacks). Abilities against enemy champions expend 4 Coins.
(Just like the Spell Thief line, the Tier 3 passive gets its minion lock-out element removed.)