You mean like auto craft? Seems like that would be a building you should pay for like food, rune, breeding boost? ( Cost 300 gems for 30 days? ) Should be toggable too!
Maybe also...
Auto food/collect: Automatically purchases highest amount of food depending on the amount of coins you have, when ready to be harvest, it harvests and auto farm back..?
Auto gold collect: automatically collects gold based on amount you want... (you can set 25/50/75/100% full to the amount when full, that it collects)
Auto breed/collect: Keeps on breeding a combination of monsters.
Idea: Slap all of this together in one building called the auto robot or something machine that cost 100 million gold to purchase and first activation is free to use for 30 days, after 30 days, purchase with 300 gems again in order to use for another 30 days?