Is your feature request related to a problem? Please describe.
"Problem" is point of view dependent here, but I do consider being able to capture Ice & Fire multiblock monsters in a soul gem to be a problem. And boss monsters from other mobs as well.
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Describe the solution you'd like
I would love it if the configs had a blacklist for creatures the Soul Gem should not be able to capture. Alternately a config that sets a max health for capturable mobs could work.
A clear and concise description of what you want to happen.

Additional context
Add any other context or screenshots about the feature request here.