how to make a halfling manticore rider?

I’ve found the Halfling Manticore Rider in the Tome of Wonders.
It’s the only t4 halfling unit I could find.
However I cannot find what must be done to actually make the unit.
What chain of buildings grants access?

I see the unit becomes available when you build the Great Beast Lair.
But I don’t have that building available in my other game.
Is it that this building/unit can only be build by a halfling warlord?