There are 3 build paths (I neglected the final item, since it has no effect on the gold income):
Path: Frost Queen's Claim
Spellthiefs Edge: Autoattack on a champion gives 4 Gold, up to once every 10 seconds. +2 Gold per 10 seconds.
Frostfang: Autoattack on a champion gives 8 Gold, up to once every 10 seconds. +4 Gold per 10 seconds.
Path: Talisman of Ascension
Ancient coin: Being near a minion's death gives 2 Gold
Nomad's Medallion: Being near a minion's death gives 4 Gold. +2 Gold per 10 seconds.
Path: Face of the Mountain
Relic Shield: Killing a minion + 5 Gold - Max. 2 Charges which recharge every 60 seconds.
Targon's Brace: Killing a minion + 10 Gold - Max 3 Charges which recharge every 30 seconds.
Assumptions
Let's say, first minion wave arrives at 2.00 minutes. Minion spawn time is 30 seconds.
- Caster minions: 15 Gold +0,5/3min
- Melee minions: 20 Gold +0,5/3min
- Siege minions: 40 Gold +1/3min (spawns every 3 minion waves)
- Considering every 3rd wave with siege minion makes + 1/3 minion per wave
- 2 waves per min = 2*6,3 = 12,6 minions / minute
Some other stuff we assume:
- First back at minute 6
- At this base we bux the upgraded version
- We neglect other items
- We neglect the time you lose while porting back and walkign down to lane
Some Math:
Path: Frost Queen's Claim
Let's assume first hit on an enemy is also at minute 2. We can trigger the passive 6 times per minute. This means:
- 6 minutes of gp/10 (12 Gold/Minute) = 6 min * 12 Gold = 72 Gold
- 4 minutes of passive (6 times/Minute) = 24 times * 4 Gold = 96 Gold
Bonus Gold at 6 minutes: 168
Now we assume to have Frostfang. Since this item doesn't depend on minion gold value we can easily calculate gold per minute.
- 4 Gold / 10 sec = 24 Gold / Minute
- 8 Gold / 10 sec (Autoattack passive) = 48 Gold / Minute
Bonus Gold income from 6 minutes on: 62 Gold / Minute
Path: Talisman of Ascension
- 4 minutes with 12,6 minions / minute = 50,4 minions
- 50,4 minions * 2 Gold = 101 Gold
Bonus Gold at 6 minutes: 101
After the upgrade we have:
- 2 Gold / 10 sec = 12 Gold / Min
- 12,6 minions / min (with 4 Gold for every minion) = 50,4 gold / min
Bonus Gold income from 6 minutes on: 63 Gold / Minute
Path: Face of the Mountain
At minute 2 we can start with killing 2 minions = 30 Gold (15 Gold each)
Then we can hit a minion every 60 seconds. Makes 4 more minions until our first back at the 6 minute mark.
- 1 Minion for 20 Gold
- 2 Minions for 20,5 Gold
- 1 Siege Minion for 40 Gold
So its 81 Gold + 30 Gold from the first two minions.
Bonus Gold at 6 minutes: 111
Now it's getting a bit tricky. We can hit a minion every 30 seconds. This means 90 seconds we can hit two melee minions and a siege minion, which gives us a total of 83 gold. (Regarding the first increase in gold bounty for the minions)
With a bit math: 83 Gold / 90 Seconds = 166 Gold / 180 Seconds = 55,3 Gold / Minute
We also have to pay attention to the rising reward which will be accountable for 6 Gold / 3 minutes.
Bonus Gold income from 6 minutes on: 55,3 Gold / Minute, which increases by 6 Gold every 3 Minutes.
Summary
Frost Queen's Claim:
- 168 Gold at minute 6
- From minute 6 it's 62 Gold / minute
Talisman of Ascension:
- 100 Gold at minute 6
- From minute 6 it's 63 Gold / minute
Face of the mountain:
- 111 Gold at minute 6
- From minute 6 it's 55,3 Gold / minute
- Increases by 6 Gold every 3 minutes