Drownyard Behemoth

Emerge let you launder a small creature into a much larger one by sacrificing it and subtracting its mana value from the cost, and this is the build that leans hardest into that conversion. The printed mana value is nine, a number nobody pays; the emerge cost of is the real price, and the sacrificed body shaves it further. What makes this particular crab worth the trouble is the separate flash keyword stapled alongside emerge, which is what supplies the instant-speed timing: emerge by itself is a casting alternative, not a window. Flash is the part that lets the colorless body land on the opponent's end step or in response to a removal spell, sidestepping the central weakness of an expensive fattie, namely that it sits in hand waiting to be answered before it ever attacks. The hexproof clause then covers exactly the turn it arrives, the moment it is most vulnerable to a kill spell aimed at the freshly resolved threat. That protection expires when the turn ends, which keeps a 5/7 from becoming permanently untouchable; it only buys safe passage through the summoning turn. The body itself is unremarkable in combat, but emerge was never about the stat line. It is about timing: turning a creature you no longer need into a flash threat that dodges sorcery-speed interaction and resolves with a shield up, then attacks before the opponent untaps. Keeping a sacrificial body around and picking the moment is a more interesting decision than hardcasting a nine-drop ever was.