There are beings in the Puella Magi Madoka Magica Multiverse that are incredibly powerful when compared to the main characters, as well as characters that are truly more horrifying than Walpurgisnacht or any witch can. The pinnacle of these is called Satanic Madoka.
Powers and Stats
Name: Madoka Kaname, Satanic Madoka, Madoka LV:9999, Bar Akemi's Worst Nightmare
Origin: Puella Magi Homura Tamura
Classification: Satanic Magical Girl
Attack Potency: Unknown (Is absurdly higher than any Magical Girl of her respective universe, destroyed Japan alongside Superhero Kyoko (Kyoko LV:9999) and Super Mami (Mami LV:9999)
Striking Strength: Unknown
Lifting Strength: Unknown
Durability: Unknown (Even the weakest human survived the destruction of Japan, this suggests that her durability is far greater than shown)
Speed: At least Massively Hypersonic (Shown to be far superior in every category to her counterpart)
Stamina: Likely Limitless
Standard Equipment: High Level Demonic Powers for Beginners (A Book)
Intelligence: Likely very high (Thanks to her book), but is possibly insane
Note: She appears only in Homura Tamura 2 and is not part of the main storyline.