MobParties

This simple mod allows you to replace all Monster spawns with a specified entity for a specified duration (in Seconds). 

Example: /startMobParty minecraft:zombie will replace all Monster spawns with Zombies for 5 minutes. You can also specify the time: /startMobParty minecraft:creeper 120 will replace Monster spawns with Creepers for 2 minutes

Party mobs will inherit Equipment, Attributes, and Effects from the Monsters they replace

Mob caps are validated so when a Party is replacing Monsters with passives, most Monsters will not be replaced. This is to ensure the Mob cap is respected. Example: /startMobParty minecraft:allay will only replace a few Monster Spawns with Allays in each chunk, since they have a small mob cap and are very laggy