Mr. Mxyzptlk (My Adventures with Superman) vs Stiyl Magnus: who would win?

Stiyl Magnus favored — Slight edge (~55%)

Mr. Mxyzptlk (My Adventures with Superman) · DC · With Bowler Hat

Tier

7-A

Attack Potency

Mountain Level

Speed

High Hypersonic

Durability

Unknown

Stiyl Magnus · Toaru Majutsu no Index · Base

Tier

7-A, up to 5-B

Attack Potency

Mountain Level, up to Planet Level

Speed

Sub-Relativistic

Durability

Small Building Level, up to Country Level

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