Dimir Midrange is also quite a grindy deck by nature, which means it will naturally accrue removal spells and interaction in the graveyard over time
None of this is likely better than Wilhelt, the Rotcleaver, but this zombie warlock might be a nice way to power down that deck while still giving you fun things to do, if thats on your radar
Echo was designed by Mike Elliot in his "Astral Ways" set before coming to Wizards, and cycling was an idea Richard had been noodling on during his hiatus from Magic design
For example, Chief of the Foundry, Etherium Sculptor, Master of Etherium, Steel Overseer and Cranial Plating all reduce your spells or make them hit harder
The larger your cardpool is, the easier it is to make a deck with the necessary sources of White, since you have access to even more good dual lands