Unity spell casting (5e Variant Rule)
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Unity spell casting
A unity spell is a combination of magic preformed by a combination of 2 casters to a maximum of 4 casters, the way unity spells work is by combining the magical energy of multiple spells together this being the case some combinations counter act each other and cannot be combined, other attempted combinations may fail depending on which spells are used for example combining radiant and necromancy spells are almost always a waste of time as both types of spells reject each other, however some radiant and necromancy spells may compliment each other which is rare in itself.
To create a unity spells 2-4 casters must be within 5 ft of each other to combine spells and must succeed on a dc 15 arcana check in order for the spell to form the spells dc increases for each level of spells used. that meaning that the highest spell slot used in the unity spell will add to the dc i.e. a level 9 spell would be a dc 24, upon completing the spell it will activate unless specifically stated that it doesn't activate immediately, to use a unity spell you need to provide the gm with a hypothesis of what you expect the unity spell to do after its completed while attempting to cast the unity spell, the gm ultimately decides the effectiveness of the unity spell i.e. its damage or effect, its duration, its casting time and other such things.
For example a potential unity spell could be combining cone of cold with burning hands taking the arcana DC into account that would be a DC 20 arcana check and by succeeding you create a water based variant of the two spells which would itself have a physical weight behind it meaning it would be able to do bludgeoning and cold damage and push the targets away by at max 15 ft this would be handy for many situations like in the elemental plain of fire or saving people from a burning building, the possibilities of unity spells are endless not only with the base spells but with the magnificent creative minds making new spells.
As a general rule it each person attempting to create a unity spell must either hold their actions to create the unity spell or have their turns directly after each other, it take an action to create the unity spell unless the gm specifies a casting time even if a spell were a bonus action it would still take an action to weave it into a unity spell, upon completing the unity spell it only requires one person to use the spell but it takes another action meaning despite the possibility endless op spells there is lots of risk involved as anything could happen in the time it takes to create the unity spell, not only that but enemies are also capable of unity spells meaning any unity spell they see you do they can potentially do it also and visa versa.