User blog comment:Jord aaan/Challenge Arena/@comment-24570336-20151024094956/@comment-26336535-20151024211247

Have you put a 5* unit in your squads? They rarely make it out of fights with 6* or 7* alive.

Unless you don't mean in "any unit" as in terms of tier, but you mean "any unit" as in terms of damage, stats, and use, then I agree. Mitigators are more viable here than in arena since SBBs won't tear down your units even if you have mitigation like in arena. Healing is almost necessary unless you can OTKO every team you go against, since HC healing is unreliable.