Rudra was the master of playing psychological warfare. He understood human psychology like no other and understood the method to manipulate a deep-set human emotion perfectly under any circumstance.
The reason why he was sitting on a tank sipping lemonade while approaching enemy lines was not because he was actually relaxed enough to chill on a tank , but because he wanted to create the illusion that he was utterly untouchable, on the tier 4 dark faction humans patrolling the walls.
Rudra understood that him displaying supreme confidence in-front of rattled individuals would make them come to terms with their most deep seated fears and that the weaker man would then psychologically crumple to a deplorable state that he wanted to instill in them.