Bind affinity casts through walls but the range is short
You can also start the cast before the group forms so if you manage to get the invite, you can accept it right before the spell hits so they won't be able to decline fast enough unless they are ready and prepared for it.
If you have any more tips or tricks to "unbind" people from firepots post here
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Okay I haven't actually done this to anyone but I'm waiting for other braver people's stories