Add an extra challenge to your runs by "locking" spells from spawning as you cast them. Like the Nuzlocke challenge for which the mod is named, this adds an extra layer of strategy onto your runs.
You might not normally pass up on adding a chainsaw to your damage wand, but if you're already close to Kolmi you might want to save it for the next run. You could start using the Add Mana you found in the fungal caverns right away, or you could save it and hope another one spawns before the Jungle.
In the settings, select whether you want spells to be queued for removal at the start of the next run, or be removed as soon as you cast it.
You can see the list of removed/queued spells in the pause menu.
Reset the spells from the mod settings menu.