Essence + Red altars

Strat explanation:

Select essence on the map device every time, this is possible due to Seventh Gate. Corrupt essences that have a purple essence (Misery, envy, dread, scorn), or 3+ shriekings. The maps I chose to run were Jungle Valley and Mud Geyser. Jungle Valley has a short and linear layout, the boss doesn't spawn so you always get "Eldritch minions gain" altars, and it can drop The Fortunate card. However, the boss takes too long to spawn, so do not kill it. Mud Geyser is a very compact map, finding all the essences is quick and you can drop boss maps from the boss. I was able to sustain these two maps throughout my 80 maps test. While you are running JV, favorite 1x JV, and MG in all the other slots. And the other way around when running MG. Also, make sure to run MG when your Exarch Invitation is ready to drop.

Generally, you want to find the essences as quickly as possible, while clicking good altars. If you got no good altars, leave the map after finding the essences and killing the boss. If you got good altars, like awakened sextants, you can clear the rest of the map.

This strategy is really profitable if you run the maps very quickly, I counted the revenue items at a rate of 40 maps per hour, or 1.5 minutes per map. This is a fast pace, but it is easily doable with a fast character and efficient gameplay. You can even get up to 60+ maps per hour with an optimized character and playstyle.

You can likely sell all your essences and Exarch Invitations in bulk for more than what Wealthy Exile says, for example on TFT. So try to do this strat for a while before liquidating, you will profit more this way.