Pulse of Llanowar

Color fixing built into the lands themselves, paid for once at four mana instead of one Birds of Paradise or City of Brass at a time. The conceit is elegant: leave your basics in place, and every one of them taps for whatever color you point it at. This was Invasion's answer to the set's whole ambition, which was getting five-color decks to function without drowning in nonbasic lands and tapped-out duals. Where most fixing trades a card or a life point per cast, this is a standing effect that touches your entire basic-land base at once, so the cost scales with how greedy your deck is rather than how many spells you cast. The friction it accepts in return is fragility and tempo: it does nothing the turn it lands, it asks for a green source to even get going, and it is an enchantment that any disenchant turns off, collapsing your mana back to its printed colors. It is the rare fixer that gets better the more lands you have, not the fewer, which inverts the usual logic of why color-screw happens. The design idea (convert basics into a private rainbow) reads as the structural cousin of effects that let a single land tap for any color, except here the conversion is distributed across the whole battlefield rather than concentrated in one permanent.