If it's large-scale group warfare, then of course the dragon form should be used. This is somewhat like the importance of cannons in a major battle; however, if it's a small-scale fight, one-on-one or a few against a few, the totem form is most suitable. In such cases, the dragon form is absolutely unsuitable.
Although the dragon form is powerful, its larger size means it's subjected to more attacks. The totem form, with humans as the main aspect, is smaller, making it very difficult to hit. Moreover... since it's smaller, there's less resistance, so it's faster, more agile, and more convenient in combat.
In the dragon form, magical artifacts are of lesser importance, but in human form, they're too important. Attack aside, their role in defense and support is almost revolutionary!
From this perspective, the value of the Chaos Cauldron is tremendously high and its power immense. It has an irreplaceable role for both individuals and the entire group.