Ice Tunnel

Two things are true of this land at once, and the second is what makes the first pay off. It produces blue or black and enters tapped, the oldest bargain in the dual-land ledger: untaxed color fixing bought with a turn of tempo. But the type line reads Island Swamp, which means it carries both basic land types and answers to anything that fetches by type. A Dimir deck running blue and black fetch effects treats this as a searchable source rather than a card stuck in the deck, which quietly changes how you count it in a manabase and how reliably you assemble both colors. Layered on top is the snow supertype: the mana it makes is snow mana, and the land itself is a snow permanent for the mechanics that scale off counting them. So a single tapland is doing three jobs, fixing, fetch target, and snow source, and the third is the only one that distinguishes it from the many other tapped duals with the same basic types and the same color output. Judged on raw rate it is slow and plain; the reason to slot it over a functionally identical non-snow Dimir tapland is that every snow permanent you run is paying into a threshold or a scaling effect somewhere else, and this one buys that threshold without giving up either the color fixing or the fetchability.