Eloquence

When to use it

A threshold affix rather than a linear one, and the clearest example on the site of why a lower-rarity item with the right affix beats a higher-rarity item with the wrong one. Below the threshold essentially anything that hits you interrupts the cast, which one creator calls unplayable for Stardust Sorcerer; above it, smaller attacks stop interrupting entirely. Both sources hedge the exact rank — one says five, the other four or five — so treat the effect as established and the number as approximate.

Builds using this

• Sorcerer — Stardust, solo and trio — Reddalf explains it at 05:30 (caption spelling unconfirmed)
  The number one priority, above five stacks. The reason is mechanical: below five, essentially anything that hits you interrupts the cast, and a Sorcerer that cannot finish a cast has no build. The creator’s phrasing is that the class is "unplayable" under that threshold.
• Seer — Reverent catalyst, ranged support — LichKArthus explains it at 10:30
  Five stacks, non-negotiable — roughly one hit of super armour every ten seconds while you are casting or channelling. This is the same floor the Stardust Sorcerer build is built on, from a different creator on a different class, which is the strongest corroboration either page has.

Where this comes from

Reddalf — Stardust Sorcerer Guide

A second source describes it independently:

• MinMax Gaming — 30+ Things I Wish I Knew Sooner — at 19:00