User blog comment:Mich, Michele & Kuhla/Q&A/@comment-128.248.111.112-20140503163900/@comment-25457866-20140503173124

This is possible through what type the unit is. Anima creatures have more HP than normal, at the cost of Recovery. Oracle creatures are the opposite: more Recovery, but less HP. Breaker, Guardian, and Lord units all have the base HP amount at max level. It is possible that the opponent has a lot of Anima creatures, but also check your own for their type.