Thran Temporal Gateway

The total cost to cheat something into play here is steep (the four to build it, then four more and a tap on every activation), which is precisely why the effect is allowed to be this broad. Most reanimation and cheat-it-in effects buy their discount by narrowing the target list: dragons only, creatures only, a mana-value ceiling. This sidesteps that entirely by keying on "historic," the game's batch term for artifacts, legendaries, and Sagas rolled into one line of text. Because that batch spans a card type, a supertype, and a subtype at once, the pool it can drop in stays colorless to your deckbuilding: any artifact, any legendary creature or planeswalker, any Saga, regardless of printed cost. The Gateway itself has no flash, so it lands at sorcery speed like any other artifact, but once it is online the activation carries no timing restriction: with four mana untapped, you can end an opponent's turn by dropping a haymaker onto an open board, dodging the sorcery-speed sweepers and answers they were saving for your main phase. What it really rewards is a top-end built around raw mana value: the bigger and gaudier the historic permanent stranded in your hand, the more the flat four-and-tap reads as a bargain rather than a tax. It asks you to load your deck with permanents too expensive to cast honestly, then turns a single batching keyword, rather than a color or a specific card type, into the key that unlocks them.