You can find them in Arena or Tournaments mostly. Clan Battles as well if you belong to a clan. They are the team that looks like Ancient Egyptian Kings or Queens. They all have a revive mechanism, where they come back as a Jar and from there fully revives. Maybe this is why the mod cant handle...
Yes, avoid against Guardians. This mod never worked against them when you use Def/Atk multiplier. Instant Win was useful, but since it is not working anymore, Guardians are immune against it.