Arien vs Luminous Being: who would win?

Luminous Being favored — Slight edge (~55%)

Arien · Lord of the Rings · Prior to entering Eä

Tier

1-A, up to HIGH 1-A

Attack Potency

Outerverse Level, up to High Outerverse Level

Speed

Immeasurable

Durability

Outerverse Level, up to High Outerverse Level

Luminous Being · Dungeons & Dragons · Base

Tier

1-A

Attack Potency

Outerverse Level

Speed

Omnipresent

Durability

Outerverse Level

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