Group Casting
A coven dressed in crimson robes gathers in a stone circle under a full moon. As they join hands, the chant begins, and a rift begins to form in the center of those gathered. At the apex of the ritual, when the moon reaches it's zenith, the door opens and the hordes of hell are unleashed.
In a grand cathedral, a procession gathers around the corpse of the hero. Each takes their turn performing the sacred rites, sprinkling holy water and lighting incense. After all is complete, the bishop lays their hands on the hero's chest, and in a flash of light their life force returns.
The highest order of the arcane university gather in a high tower. In rehearsed motions and rituals, they combine their magical might to divert the oncoming meteor. In the town below, the commoners are none the wiser to the averted disaster.
By combining their abilities, a group of spellcasters may work together to cast spells beyond their individual capabilities.
Beginning Group Casting
To begin group casting, one character engaged in the casting must know the spell, or have access to suitable instructions, such as a spellbook or scroll. A member of the group is designated the lead caster, and they are the person who casts the spell when the casting is complete. During group casting, all members must remain within 60 feet of the lead caster, and it is their spellcasting ability that is used for the spell.
The first step in group casting is to determining the amount of Spell Points required to cast the desired spell. The amount is primarily based on the spell slot the group is attempting to collectively generate. The group can decide to create any spell slot level in the casting of the spell, and the spell is affected by a higher level spell slot as normal, if applicable.
Spell Slot Cost
| Spell Slot Level | Magic Point Cost |
|---|---|
| 1st | 4 |
| 2nd | 7 |
| 3rd | 12 |
| 4th | 15 |
| 5th | 18 |
| Spell Slot Level | Magic Point Cost |
|---|---|
| 6th | 23 |
| 7th | 26 |
| 8th | 29 |
| 9th | 34 |
Generating Spell Points
Each caster contributing to the group casting of the spell can expend one spell slot to generate magic points towards the group casting. The amount of magic points generated per spell slot level is given in the Spell Point Cost table.
Characters can also generate Spell Points at the expense of their physical well-being, even if they do not have any magical ability. A creature engaged in group casting can choose to gain levels of exhaustion to generate a number of spell points equal to the number of levels gained.
Spell Point Cost
| Spell Slot Level | Spell Points Generated |
|---|---|
| 1st | 2 |
| 2nd | 3 |
| 3rd | 5 |
| 4th | 6 |
| 5th | 7 |
| Spell Slot Level | Spell Points Generated |
|---|---|
| 6th | 9 |
| 7th | 10 |
| 8th | 11 |
| 9th | 13 |
Finally, Spell Points can be generated for group casting by sacrificing magic items. Magic items sacrificed this way are reduced to dust on the completion of the casting. Only one of each type of magic item can be used in this way. The spell points generated are based on the rarity of the magic item sacrificed, as shown in the Sacrificing Magic Items table.
Sacrificing Magic Items
| Magic Item Rarity | Spell Points Generated |
|---|---|
| Common | 1 |
| Uncommon | 3 |
| Rare | 6 |
| Very Rare | 9 |
| Legendary | 11 |
Casting Time
Due to the complexities of casting a spell as a group, the casting time may increase. Consult the Group Casting time table to determine the minimum casting time of the spell. The casting time is equal to the time generated or the original casting time of the spell, whichever is higher.
Group Casting Time
| Casters | Casting Time |
|---|---|
| 2 | 1 minute |
| 3 | 5 minutes |
| 4 | 10 minutes |
| 5 | 30 minutes |
| 6 | 1 hour |
| Each caster beyond the 6th | +30 minutes |
Additional Effects
The lead caster can add any relevant class features to the casting of the spell. For example, if the group is casting Animate Dead and the lead caster is a School of Necromancy Wizard, their Undead Thralls feature applies to the casting.
The group can also add additional effects to the spell by increasing the point cost. Each member of the group can add an additional effect to the spell, and additional effects may be added multiple times by different creatures. The cost of adding additional effects is given in the Additional Effects Cost table.
Additional Effects Cost
| Additional Effect | Point Cost |
|---|---|
| Accuracy Boost | 2 |
| Additional Target | Variable |
| Area of Effect Increase | 4 |
| Extra Damage | 3 |
| Greater Range | 1 |
| Longer Duration | 2 |
Accuracy Boost. The spell save DC or spell attack modifier used for the spell is increased by 1. This effect can be applied a maximum of 3 times.
Additional Target. The spell can target one additional creature or object. The cost of this effect is dependent on the level of the spell being cast, as shown in the Additional Target Cost table.
Additional Target Cost
| Spell Level | Point Cost |
|---|---|
| 1st | 1 |
| 2nd | 2 |
| 3rd | 4 |
| 4th | 5 |
| 5th | 6 |
| Spell Level | Point Cost |
|---|---|
| 6th | 8 |
| 7th | 9 |
| 8th | 10 |
| 9th | 12 |
For example, when applied once to animate dead, the effect costs 4 spell points and allows the spell to animate or reassert control over one additional undead creature.
Area of Effect Increase. The area of the spell's effect is increased by an amount equal to half the base area (round up). For example, when applied to fireball, the area of effect becomes a 30-foot radius sphere.
Extra Damage. The number of damage dice dealt by the spell is increased by an amount equal to a quarter of the base damage (round up). For example, when applied to lightning bolt, the damage dealt becomes 10d6 lightning damage.
Greater Range. The range of the spell is increased by an amount equal to a half of the base range (round up). For example, when applied to daylight, the range becomes 90 feet.
Longer Duration. The duration of the spell is increased by an amount equal to the base duration (round up). For example, when applied to clairvoyance, the duration becomes Concentration, up to 20 minutes.
Interrupting Group Casting
If a creature is damaged while engaged in group casting, they must make a saving throw to retain concentration on the spell as they would if normally casting a spell. If they fail, the casting continues but the creature's contributed spell points and additional effects are lost (including the cost of the additional effect). They can regain concentration on the spell using their action, and can apply additional effects and contribute spell points as normal again.
If the lead caster loses concentration on the spell, the casting fails and any expended resources are wasted.
Finishing Group Casting
At the end of the group casting, the lead caster casts the spell as they would if casting the spell normally, including any additional effects applied. If the spell requires concentration, members of the group may choose to continue concentrating on the spell. The spell continues as long as at least one creature maintains concentration on the spell.
Example Scenario
For example, a group of cultists are attempting to cast meteor storm to destroy a cathedral. As the spell requires a 9th level spell slot, they must generate a total of 34 spell points.
The lead caster is a 10th level evocation wizard, and the group is made up of 3 cult fanatics and 7 regular cultists.
When they begin casting, the lead caster expends a 5th level spell slot to generate 7 spell points, each cult fanatic expends a 2nd level spell slot to generate 9 spell points, and each cultist gains 2 levels of exhaustion for a total of 14 spell points. Finally, the group sacrifices a +1 dagger for the final 2 spell points.
Being a 10th level evocation wizard, the lead caster can apply their Sculpt Spells and Empowered Evocation class features on a successful casting.
With 11 people performing the casting, the spell takes 3 and a half hours to cast - plenty of time for the heroes to intervene and halt the evil act.