Hall of Heliod's Generosity

Enchantment recursion, folded into a land slot. The bargain a colorless-producing utility land makes is that the value engine rides for free on a source your deck was going to run anyway; here the engine rebuilds white's permanent type turn after turn. The tax is deliberate and comes in two parts. First, the activation is not free, costing white plus one on top of the tap. Second, and more limiting, the enchantment does not return to your hand: it goes back to be drawn, so you buy the permanent back a turn late rather than on demand. That single restriction defines who wants this. It is a poor tutor for the deck scrambling after one specific answer in a hurry, and an excellent one for the deck that keeps redeploying the same locking or grinding piece (a repeatable board-clearing enchantment, a game-warping prison effect, a graveyard hoser) once the game has slowed to a crawl. Structurally it maps the older colorless lands that rebuy artifacts and equipment onto white's core permanent type, doing that same recursion work in a different color's idiom. Because the toolbox lives on a land, it costs no card in the deck and sidesteps the sorcery-speed spells that fill the same role: run it as a late land, and the recursion is simply available whenever a game grinds long enough to reward it.