When this card is activated: Look at the top 3 cards of your Deck, then you can reveal 1 "Dark Magician" or 1 Spell/Trap Card that specifically lists the card "Dark Magician", among them, and add it to your hand, also place the remaining cards on top of your Deck in any order. If "Dark Magician" is Normal or Special Summoned to your field (except during the Damage Step): You can target 1 card your opponent controls; banish it. You can only use each effect of "Dark Magical Circle" once per turn.
How to Get
Able to look at the top 3 cards of your deck and arrange them in any order.
Can add a Dark Magician, or a Dark Magician spell/trap if it's in the top 3 card.
Summoning a Dark Magician lets you banish a card your opponent controls.
Only able to add to your hand a card that is related to Dark Magician.
Search for Dark Magician's spell/trap cards from your deck by using Magician's Rod, including Dark Magical Circle, which can be used right away for a potential +1 if there's a card related to Dark Magician, or to simply re-arrange the top 3 card of your deck. Alternatively, you can summon Magician's Rod to get Illusion Magic from your deck to draw 2 DM from your deck, then you can use A Hero Emerges to special summon one of them.
Legion the Fiend Jester helps with tribute summoning for your DM so that you can activate Dark Magical Circle's second effect. Use Dark Magic Curtain to summon a DM from your deck and banish a card. If it survives for another turn, then you can normal summon Fiend Jester and go into another DM to banish another card your opponent controls.
Dark Magical Circle is best used in a deck mainly focused on Dark Magician. There are already several support spells that it can be used with, and it provides some versatility in the deck, but it's better not to include everything since it can be a dead card in your hand if you don't have a DM on your field. You can also use Arkana's Master of Magicians skill instead of having to bring different ones in your deck.