To farm Odile's hippo stacks on area 5 you need to use Dr. Evil to drop DPS to 0. That way only Odile's hippos are killing anything. It takes a couple of hours to farm 1500 stacks, but if you use Mindy to mime Odile, that time gets cut in half. For more in-depth info, feel free to join the unofficial community Discord: https://discord.gg/vYrMAnax

You can go back down to area 5 to farm boss kills for Odile once you've earned enough gold to unlock all the upgrades you need.

Otherwise, players are able to unlock all the upgrades they need once they've got a high enough idol count for monster kills in area 1 to drop the gold amount to do it.

You need to have a bunch of Animal tagged Crusaders in your formation that are infected, and the Humane Testing upgrade enabled and purchased, if you want the DPS to zero out.

You may also need a higher level of Legendary Eye Patch on Dr. Evil, so the infection lasts long enough to infect all the Crusaders you need infected.

The Bossing Around talent removes the normal monsters that spawn on a boss area, so that definitely helps with getting the boss kills.

Or if you can use the active abilities quicker, you can use Bruno with his 5th slot rune equipped and build up his Marvelous Gold stacks.