User blog comment:Lasatar/How Shulk should have been done/Shulk moveset for Smash 5./@comment-24416652-20160405140342/@comment-25275196-20160405215246

No, that's tension in Xenoblade X. In the original, depending on how high the tension is, the facial expression of the character's portrait changes. The higher tension is, the higher a character's agility and accuracy. The lower tension is, the lower it is. You can get tension by scoring critical hits, or dodging an attack, and by some other means. You can lose tension when a fight isn't going well and you are missing attacks, or the enemy is blocking them, along with some other means.

It's a difficult concept to explain, but the general gist is this: the higher tension is, the better the character will perform.