Income

Purchasing income in the Power Ups Shop II will also increase the strength of creeps.

It takes 13 rounds for any income upgrade you bought to pay for it self (1150/90=12.777....) so unless your plan is to kill the enemies using creeps it's not worth buying income upgrades after round 36 (12 if you're playing 25 rounds). It is recommended to purchase income upgrades before the PVE round is over as you will get gold for the upgrades you purchase during the rounds.

Buying income upgrades will increase the power of creeps more for the creeps you are fighting than the ones your enemies are fighting

This table shows how much power the creeps get with each income upgrade you buy. Creeps can not gain power during rounds, it will apply the round after you purchase the upgrade.

* If the individual creep upgrades setting is on you will only upgrade your own creeps.