Magic Circles are a magic construct that appear in Hyrule Warriors and Hyrule Warriors Legends. They allows their users to preform various magical feats such as summoning magic chains or used to summon the aid of powerful beings like the Great Fairy. They are usually created by the magic of a powerful magic user such as Princess Zelda, White Sorceress Lana, or Twilight Princess Midna. One interesting aspect of the Magic Circles is that they seem to require the use of prayer to activate them (either to the Gods or the Great Fairy).
In combat, some characters use Magic Circles as part of a specific weapon's moveset (either via a combo, Special Attack, or Focus Spirit Attack) to summon something (such as a creature or object) and/or to cast powerful spells. As part of her Rapier moveset, Princess Zelda will use a Magic Circle to create a ball of light which she hurls at enemies as one of her combos and also to cast Nayru's Love, Farore's Wind, and Din's Fire as part of her Focus Spirit Special Attack. As part of her Giant Blade moveset, Impa will use a Magic Circle to create/summon four Giant Blades made of water and in her Naginata moveset Impa uses a Magic Circle to summon six giant Naginata blades and a fiery version of the Sheikah Emblem as part of her Naginata's Special Attack. As part of her Book of Sorcery moveset, Lana uses Magic Circles to summon magic walls and blocks during certain combos or attacks. As part of her Spear moveset, Lana uses a Magic Circle to summon either three mini-icebergs and three Deku Tree Sprouts to attack enemies as part of different combos. As part of her Parasol moveset, Agitha uses Magic Circles to summon giant Golden Bugs such as a giant Beetle and giant Butterfly. As part of his Hammer moveset, Darunia will use a fiery Magic Circle to summon a giant molten boulder to throw at his enemies. As past of his Great Swords moveset, Ganondorf uses a dark magic circle to summon a shadowy version of his Ganon form to attack enemies with a claw swipe and when his Dark energy gauge is full he will use a Magic Circle to create an explosion of dark energy as his Strong Attack. As part of his Demon Blade moveset, Ghirahim uses a Magic Circle to summon a ceiling of geometric shapes which he slams enemies into during one of his combos.
A Magic Circle's color appears to indicate the element of Magic it produces such as a red colored Circle produce fire-based attack/spells, a blue colored Circle produces a Water/Ice-based attack/spells, a Yellow colored Circle produces Light/Electric-based attack/spells, and a Purple color produces Darkness-based attacks/spells.
In The Sorceress of the Valley, Link accidentally triggers a dark magic circle Cia had placed near the Gate of Souls, which traps Link, Sheik, & Impa (Lana manages to escape as she is able to recognize the Circle is a trap) allowing Cia to steal the Triforce of Courage from Link and the Triforce of Wisdom from Sheik (Zelda in disguise). Cia also uses a similar Dark Magic Circle to briefly seal away Ganondorf after he regained his physical body after Cia had freed 3 of his soul fragments. However it should be noted that she was only able to seal away him briefly and she cast it when Ganondorf was distracted by her returning the Triforce of Wisdom and Courage back to Zelda and Link. At the time, Ganondorf also lacked the Triforce of Power which was in Cia's possession and the fourth fragment of his soul was still under seal by the Master Sword.
Lana has also demonstrated that they can be used to summon allies from across time (Darunia, Princess Ruto, Fi, Midna, and Agitha), though her ability to do this may be due to her having once been a part of the Guardian of Time. Ganondorf also uses two Magic Circles to summon the revived Ghirahim and Zant to Gerudo Desert to be generals in his army.
In Hyrule Warriors Legends, Magic Circles also appear in certain Adventure Mode scenarios and can be used to decimate enemies. In order to activate them, the player must escort an ally to a Keep on the battlefield (if the Keep is controlled by the enemy it must be captured). Once the Magic Circle appears it can be activated to take out an enemy force.