The further towards the bottom one draws, thge greater the chances of the structure collapsing are. The same goes for draws from the middle when an edge block is drawn, or draws from the edge when the middle block has been drawn. In essence, you must be mindful of the center of gravity to avoid collapsing the tower. But in doing so you leave the tower considerable stability for the opponent to work with, which will land you back in the same situation once they've drawn, with gradually decreasing chances of success. This mean the most assured strategy is place your life on the line, and make the riskiest moves leaving the opponent know chance to counter. It's a kill or be killed strategy which leaves no room for cowards and the first to chicken out will be buried underneath the rubble. The sand is in hell is magical sand.