How to Use Sauna
Sauna is a gamble that's often well worth the risk. Especially in situations where your opponent is bursting down your front line within seconds, one of those minis can potentially 1v6 the entire opposition after emerging with Super Power. Super Power boosts attack speed, move speed, and damage in addition to keeping any stat boosts the mini had prior to being knocked out.
Sauna has the lowest health of all gizmos, making it impractical as a defensive option. That said, it can still be useful to shield a backline mini if you're confident your first KOed unit can emerge from it early in a round. Sauna is also not recommended, or at least highly situational, while playing Barbarian King or Witch.