Mournwhelk

Two prices for the same hand attack, and the gap between them is the whole story. Cast it for the full and a 3/3 sticks around after target player discards two cards; pay the evoke cost of instead and the Elemental sacrifices itself the moment it lands, leaving you nothing but a four-mana Mind Rot. The full cast is wildly overpriced for the discard alone, which is the design's signal: the body is the tax you pay for keeping the creature, and three extra mana for a 3/3 with no further upside is a tax most boards will not pay. Evoke turns the same effect into the leaner deal, the discard for a card and four mana, with the Elemental made optional rather than forced on you. What evoke does not buy is any timing edge. This is a creature without flash, so both modes are stuck on your own main phase: you cannot hold it for an opponent's end step or strip two cards from their grip before they untap and draw, the way an instant-speed disruption spell could. You are choosing between two versions of one effect, not a better window into it. Spending four mana and a card to take two of theirs while developing nothing is a rate the game has long since outgrown; the construction is tidy, the math is not.