The Charmers are a fan favourite archetype of cute girls (and a sad boy), that originated in early ygo as FLIP monsters that can take control of a monster your opponent control with their same original Attribute. Over time they have gotten more support that has made them usable, but not viable. The Charmers' Familiars recieved upgrades as well, becoming excellent extenders while you control a Spellcaster monster. One stellar piece they recieved was Eda the Sun Magician, which Special Summons a Spellcaster with 1500 DEF, such as a Charmer, from your Deck in face-down Defense Position. It can also flip up a face-down Spellcaster you control during your opponent's turn at Quick Effect speed.
Combine all this with the powerful Dogmatika Engine, which provides further extension, disruption, and utility, which makes this deck much more competitive, but nowhere near tiered status.
If you want to play the Shaddoll Engine, you can easily exchange a few cards out for it, and you'd probably want to add another Maximus too.