Bubbling Muckramp$2.45If you want black mana acceleration, this massively boosts Swamps for a turn and can enable explosive plays. It fills the same broad role of helping produce more black mana, though in a spell form rather than a creature.
Jet Medallionramp$12.59A black cost reducer that effectively accelerates your black spells over multiple turns. It serves a similar mana-acceleration role in mono-black decks, especially when you want sustained advantage rather than a one-shot mana dork.
Charcoal DiamondrampBudget$0.71A direct artifact mana-rock analogue that enters tapped and then taps for black mana. It is one of the closest functional replacements for Leaden Myr in black decks.
Coldsteel Heartramp$0.99Another 2-mana mana rock that can produce black mana and fits well in color-focused decks. It is slightly more flexible than Leaden Myr because it can be fixed for any color at the cost of entering tapped.
Fellwar Stoneramp$1.91A cheap two-mana rock that often produces black mana in multiplayer and supports the same early-game acceleration plan. It is usually stronger in Commander while still filling the same role.
Prismatic LensrampBudget$0.38A budget two-mana rock that can help filter into black mana and accelerate you on turn two. It is not as direct as Leaden Myr, but serves a similar early ramp role.
Skyclave Relicramp$1.24A more durable mana rock that can make black mana and scales into the late game thanks to kicker. It is a strict upgrade in resilience for decks that value artifact mana.
Sol Ringramp$2.97The premier generic mana accelerator and a strict upgrade in raw speed. While it does not specifically make black mana, it fulfills the same early-ramp function in nearly any deck.