Unison Magic is a caster type magic that requires two or more Wizards to prefrom allowing them to synchronize their Magic Energy and doing so release highly powerful spells.
Multiple Caster Type
Unison Magic is the act of linking Magic Energy between a group of Wizards in order to greatly increase their Magical Power. Magical Power which is the physical sense of Magic Energy released directly from a Wizard. This is rather faint when coming from an average Wizard but when connected to other Wizards through Unision Magic, the Magic Power combines and amplifys greatly increasing the magical output of each of those Wizards which intern allows them to preform highly powerful spells.
Unison requires calmness of mind and for each Wizard to match their Magical Power with one another in order to empower each other. Which is difficult to maintain unless each of them are in balance and is why most Unison Magic is limited to about three Wizards but more commonly used by two yet it is more powerfull with the more Wizards in the group.
Even after Unison is created it is still difficult to maintain a stable flow of Magical Power. Meaning it requires constant focus and teamwork between each Wizard.