Flameheart is accepted.

Just so you know I am picturing Transmetal 2 Megatron but with a more mechanical look when I think of Flameheart.

The series of caves that lead to the base are tall enough for say Megatron to stand in but the base area is only big enough for say Bumblebee to stand in comfortably. Your character while in base would have to remain in dragon form or stay outside of base all the time.