Tanglepool Bridge

What kills lands? Wasteland, Strip Mine, and the whole pile of artifact-and-land destruction that punishes greedy manabases. This one shrugs all of it off. Indestructibility on a mana source reads like a marginal upside until you remember that the effects most likely to blow up your color base are precisely the ones that destroy, and this survives them intact. The keyword is not universal armor, though, and it is worth keeping the distinction straight before leaning on it: type-changing and ability-stripping effects leave the permanent on the battlefield but hollow it out, and nothing here answers that class of hate. Where it earns its slot is against decks trying to remove your mana outright. Because it is an artifact land, it also feeds the affinity-style economies that count artifact types, doing so without asking the deck to run fragile mox-shaped pieces that die to the same removal it ignores. The design tension is clean: the enters-tapped clause is the whole cost, so the card only wants a deck that can afford to set up a beat behind and expects its lands to come under fire later. That is a narrow but real profile. This is not the dual you run for smooth mana; it is the one you run because you have decided your lands are targets and would rather they not die.