Doppelgänger Demon vs Surtur (Marvel Cinematic Universe): who would win?

Surtur (Marvel Cinematic Universe) favored — Slight edge (~55%)

Doppelgänger Demon · Godzilla · Base

Tier

HIGH 5-A

Attack Potency

Brown Dwarf Level+

Speed

Supersonic

Durability

Brown Dwarf Level+

Surtur (Marvel Cinematic Universe) · Marvel · Eternal Flame

Tier

LOW 4-C, up to 4-B

Attack Potency

Small Star Level, up to Solar System Level

Speed

Superhuman, up to Subsonic

Durability

Small Star Level, up to Solar System Level

A heuristic estimate from normalized VS Battles Wiki stats: tier, attack potency, speed and durability.