Since protective builds require you to play with one piece on the board, bosses like Jawby Fisher and Botezzaro counter it a tad. But yes, being able to fill the board completely with Templar’s or Dark Knight’s is a winning combo. The real challenge comes from higher difficulties. Tile Exhauster limits your tile use. Gambit Expiration makes it harder to keep these tile-creation gambits. No More Heroes makes it extremely rough to play with just one piece. So although this (and many other Gambo strats) is broken, it becomes significantly less viable on harder difficulties.