[Condition] Max Self Mob (Count how many of a mob exists)

My suggestion is a condition that counts the amount of a mob that exists.
You'd either be able to do a range, a value, or a greater-than/less-than, just like the mobsinchunk/word conditions.
So, you'd be able to use this in randomspawns to only spawn in a mob if less than a certain amount already existed, providing a cap on how many are in the world/area.

You could also use this to make an ability that only works if over a certain number of the mob in question exist. (Like a charge up move...

[Condition] Max Self Mob (Count how many of a mob exists)