How to Block a Specific Mob Entirely With the Mob Filter Command

Use the deny command

Mob Filter exposes an in-game command for quickly blocking a mob without hand-editing the config. The pattern is /mobfilter <mob> deny, where <mob> is the mob you want to remove from spawning. For example, to permanently stop creepers from ever spawning, run /mobfilter creeper deny.

This writes the rule into your config for you, so you don't have to know the file syntax. Run it while you have the necessary permission level (single-player or operator status on a server).

Confirm and manage the rule

After running the command, the mob should stop spawning world-wide. To check what rules are active, use the mod's command to list current filters if one is available. If you later want the mob back, remove or reverse the rule — either through a matching command or by editing the config file directly and reloading.

Because a command-created deny applies everywhere, use it for mobs you genuinely never want (like a nuisance mob in an adventure map). For mobs you only want gone in certain places, prefer a config rule with biome or coordinate conditions instead. Always reload after manual edits so the change takes effect.