The Scroll of Control is often better than Pandora's Box for controlling the entire map. What is easier and more effective: to increase Wisdom, defeat Pandora's Box, and use it with one hero, or to defeat the Scroll of Control and use it with all heroes? And most importantly, consider all the timings (exits to the third tier, hero leveling). The earlier this scroll is obtained, the more effective it is than any Pandora's Box (in practice).
In the Mirror map, the game and luck (as a part of the game, of course) come down to finding these scrolls, which is already incorrect.