A few economy items

[Lifeland]

Atmospheric soul collector -t1
Passive:
This item's sell value increases by 200 souls every minute, or 300 per min if a neutral entity was killed within a minute. this item's maximum sell value is 1000. If the player who owns this item is killed, they will drop a red soul cage. Whoever picks up said cage will receive this item with its current sell value.

Spirit harvesting kit -t3 (upgrades from monster rounds)
Passive: 10s CD
If at the end of an damaging ability's duration: no enemy heroes took damage, refund 60% of that ability's cooldown.

 

[Rosgath]

I like the idea for the Atmospheric Soul Collector, but I don't think it needs the extra Red Soul Cage effect. I would also reduce the "Increased sell value" to 50 souls per minute, but have it gain 200 sell value whenever a Hero is killed or the player is near a destroyed enemy objective (this would be until it is sold) and I'd raise the cap to something like 1200. Overall you are only getting something like 400 souls and it's a medium-term investment.

As for the Spirit Harvesting Kit, I like the concept but let me propose a different way for it to function that uses mechanics already in game:

Passive: 18s CD
When you kill an NPC, reduce the CD on all of your non-ultimate abilities by 6s. This effect goes on CD for 10s after you damage or are damaged by an enemy hero.

This would make it a lot easier to farm camps for some heroes, though it does favor heroes who are already hyper farmers. Ideally there would be an item to prop up heroes who can't farm as quickly that is relatively cheap, but I'm not sure what would work that wouldn't just make Hyper farmers better at farming than they already are.