Eluge, the Shoreless Sea

A "power equal to Islands you control" body has existed for decades, and it was always a static curve: your creature is as big as your land count and nothing else follows. Here the flood counters make the same statistic feed two engines at once. Each counter turns an arbitrary land into an Island in addition to its other types, which grows the elemental, and it simultaneously trims the first instant or sorcery you cast each turn by a mana per flooded land. That "in addition to its other types" clause is the reach of the design: off-color duals and utility lands you already control start counting toward both the size and the discount the moment a counter drops, no basic Islands required. The reduction is capped at one spell per turn, which keeps the payoff from spilling into a storm-style chain and instead rewards banking a single expensive spell to cast for free or nearly so. Because both the enters trigger and the attack trigger place counters, the growth is stapled to combat rather than passive accumulation, so the card wants to be swinging even as it builds toward an unanswerable board. It reads like a control finisher and a tempo threat sharing one coat: a clock that funds your interaction as it grows, in a color long forced to pick between the two.