Thanks for cogitoergosum815 for this idea: The Anubis Robot!
What is so special about it? It's a Diamond-tier mini-boss (Kind of like Spidertron) That appears along with some MK3 Robots, it's abilities include attacking with it's spear, and summoning MK1 Robots from the ground! It has a stronger version, that appears in Titanium-tier, which is silver colored, that can summon MK2 Robots, but this one appears alone. Also, when the battle starts, there are multiple Ankhs scattered around the arena, if you kill the "Anubis" without first destroying the Ankhs it will simply rebuild itself! The MK2 version scatters more Ankhs around.
Full names: MK1 "Anubis" Reanimator Robot, MK2 "Anubis" Reanimator Robot