One such card could be Cecil, Dark Knight, which costs 1 Black mana for a 2/3 Legendary Creature with Deathtouch, but it arguably has a downside that is not necessarily its Darkness ability, but the fact that one can't have multiple copies of this card on the battlefield at once
But that's just speculation at this point
This two-drop will draw when an Equipment ETBs not a cast trigger, sure, but in the same space as that deck archetype
Every mana counts here, so on turn three, if your plan is to cantrip further, you should try to hold back your land drop if possible
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions (such as that of Mutated Cultist's second ability)