Growth of for-hire creatures

[Metathron]

Nope, as far as I know the majority of creatures offered in the game come in a limited supply. Exceptions are creatures in King Mark's castle (later on, at least) and maybe some other places as well, but not many.

[Calinda]

Not only the castle, when you get promotions (like baron, earl, etc.) or on certain quest/event completions you usually get new troops in related castles or hiring locations.

[Gatts]

Most castles re-supply if you do specific quest for them - dwarven king : after you free his son, Elven princess, after you defeat Korador, The castle where the magic academy is : 1. after first barbarian peace sign, 2. after second barbarian pease sign (I choose fight instead second peace sign )

[lauvhk]

Hey, fighting the barbarian is the only way to complete the quest, you know.

Back to the question. When the creatures number turns into "Horde", the supply becomes unlimited. Of course, you need to work towards that like the others say.