Oh, as an attachment for the nest idea...Great ideas. I like the idea of spiked heads. Also some sort of wall defense thingy is definitely coming maybe caltrops, barbed wire, and some sort of hidden spikes. I should be putting some more features in by tomorrow. Right now Im working on exporting objs and importing them as java so I can start having models.
I think it would be awesome if you could accelerate the egg hatching process by putting a heat source near it. And if there are tamed adults nearby of the egg type being nested they would sit on it to provide a faster boost. But keep in mind, nests are flammable (at least the entry level ones should be. Perhaps you could later make phoenix nests using stone sticks and blaze rods that automatically provide the heat.
Maybe roosts too. Like rods you could put on vertical surfaces to make an out jutting perch for a phoenix to rest on.