The walking siege engines of the Cosmic Era
The Rocky Mountain Republic owes in large it's existence to a single limited run of primitive mechs, the Assault/Bombard Mech model 1.
T'was a great roar, milord, and the ground was rent and the horses took their bits in their teeth and there was much confusion. No magic could reach so far, and none of our magehounds scented wizards. We do not know the deviltry of the enemy, and for this we lost the battle.
The spellbook of a long dead wizard that has gained the ability to read itself and cast spells from itself. If could be amazingly powerful as an ally, or use its magic to manipulate and rule a kingdom.