Eldrazi Temple

The trick that makes the Eldrazi ramp curve work isn't a creature or an artifact: it's a land that taps for a single colorless to anyone, then offers a second mode adding two at once, spendable only on the colossi it serves. That second ability is the reason the original Eldrazi titans, the ones whose costs ran into the double digits, were ever castable on a sane clock. The bonus only flows toward colorless Eldrazi, which makes it a tribally-locked accelerant stapled to an otherwise unremarkable colorless source: it compresses the curve without doling out a blanket boost to every nontribal spell in the pile. That restriction is the entire balancing act. A land that simply tapped for two would slot into anything willing to run a colorless source; tie the surplus to one creature type and the payoff only materializes once you've committed to the things it powers. The forward compatibility was baked in from the start. The original wording already restricted the bonus to colorless Eldrazi spells, so when the type was later reimagined as colorless creatures with devoid, the land kept ramping the new generation without a single change of text: devoid makes those creatures colorless by definition, and the qualifier was already there to catch them. With that built-in flexibility, it has anchored every Eldrazi shell since, from the eldritch giants down to the cheap aggressive creatures that turned the type into a constructed mainstay.