Boon Invocations to feel like a coven

So this is a rule that I am workshopping for a fantasy campaign. Several of my players are spellcasters, and they wanted to have that feeling of a coven that works together to cast a spell more powerful than any member could cast alone. This is what I came up with so far. I would really appreciate thoughts you guys have to make achieve this feel, but also balance it a little bit.

Group Casting

Characters with extraordinary attributes and access to the same boon may all roll to invoke the boon at the same level at the same time. The invocation time of the boon is increased by one time category if invoked in this manner. If the majority of the players passes the roll (i.e. ⅔ or ⅗), the boon is invoked at one power level higher than the power level rolled. Every player must maintain the boon. If one player stops maintaining the boon, its effects stops for all players involved.


It’s a neat and simple house rule, not too powerful either.

Perhaps it work best as an addition to Tier II of Heightened Invocation, which already allows group casting.


I hadn’t thought of combining it with heightened invocation; I will have to look into it, but I wanted to avoid making players pay to do group casting.

I can understand that.

Then again, there’s already “smaller” forms of group casting which don’t require much investment via the Assist Action, the Bolster Boon and similar mechanics which can be flavoured as group casting. Heightened Invocation II is just “the next step” in that context.

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The problem with assist and bolster is that they put the dice roll of the desired boon on the one character. This method lets everyone roll for the desired effect.

So, only 1 player has to pay for the group casting, the others just need the access via being able to do the boon or the bane.

Whereas not as many are rolling if you do it via heightened, it also helps there not be as many rolls and higher chance of success with additional advantage possibilities.

You could do it, that by being in the coven, you have access to Heightened Invocation without the feat point cost, but as a result, everyone involved has to sustain it like you suggested. So the cost of getting it for free by being in a group is the higher cost of sustaining.

You could still do it just like heightened, and get the other benefits of adding in more people by picking other additional things, and if you really wanted everyone to roll, then if their roll isn’t successful, the thing they were adding from heightened invocation doesn’t happen

You make good points. I’m very torn on this rule. I was proud of it when I made it, but I forgot about heightened invocation.

Heightened Invocation is quite niche, so it’s rather easy to overlook, but your idea is very similar in spirit. You could easily add your idea to the list of options and thus integrating both into each other.