>>11274393He's a regular sized light blue skinned guy sorcerer who wears a red robe and mummy wrap in lieu of actual clothing and has a pug as his pet who is the only being he's nice too. In spite of what casuals might think, he's actually a third party villain in Thundercats; the mutant villains woke him up when they found his pyramid base (which he is stuck in, as he has to constantly sleep in a special crypt coffin and can only be out of it for 24 hour periods without dying) and woke him up.
Normal Mumm-ra is a generic sorcerer who specializes in illusion magic. He however, can borrow power from four "dark gods" to power up into his form that everyone associates with him (called Mumm-ra the ever living) which is basically Super Sayian Mumm-ra.
This form is insanely strong and tough, think Superman tier super strong, along with being the height of about two people. But he has two weaknesses: Sunlight straight up depowers him and turns him back to normal and a never explained curse that causes him to feel unspeakable physical pain if he sees his reflection.
As such, he's a cool character but super fucking lame in practice. He rarely leaves his base or uses his super form and if he does go out, he's in disguise. And his size issue makes him hard to translate into actual figure scale unless you say fuck it and ignore scale.
As far as best figures, either the Super 7 version (if you want a big Mumm-Ra who is show accurate) or track down the 2011 deluxe Mumm-Ra who IIRC can scale with Marvel Legends but just barely.