Cataclysmic Charmer is a series of Level 4 SpellcasterEffect Monsters with 800 ATK and 1500 DEF that debuted in Enemy of Justice. All Cataclysmic Charmers are older versions of the "Charmer" and "Familiar-Possessed" archetypes, with their familiars reverted to their original forms. There is one Cataclysmic monster for each of the 4 elemental Attributes: WATER, EARTH, FIRE and WIND. They share the effect of Tributing a face-up monster of their same Attribute to Special Summon another monster with that Attribute, as well as the weakness of destroying any monsters Special Summoned by their effects when they leave the field.
A good way to protect your Cataclysmic Charmer monsters is to equip them with "Heart of Clear Water" or "Mist Body", since they are vulnerable to being destroyed by battle. Then use the effect of your Cataclysmic Charmer to Special Summon monsters with high ATK that would require more Tributes to bring out, such as "Gogiga Gagagigo" or "Beast King Barbaros". One good strategy is to use "Stumbling" to keep your Cataclysmic Charmer from being attacked by your opponent's monsters each time they Summon new monsters. Then use of "One for One" to discard a monster and Special Summon 1 of any Familiar, except "Fox Fire", from either your hand or Deck. As long as you have the right Attribute on the field with the appropriate Cataclysmic Charmer, you can Tribute the monster (or Familiar if you preferred) to Special Summon a monster that would require 2 Tributes from your hand. The Attribute Summoners are also an efficient way to bring monsters from this series to the field.
All familiars of the "Cataclysmic Charmers" had reverted to their young, normal selves rather than evolving into more advanced forms, the exception being "Gagagigo", which has more forms as seen in the Gigo series.