What things REALLY mean in POE

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Perfect_Black wrote:

Every monster affix that starts with "Allies..." means "Allies and This Monster..."
accept for "Allies Cannot Die" ... that one actually only applies to "Allies".

Allies means all things on the same team. Things on different teams are enemies. A monster by definition is it's own ally - it's on the same team as itself.
The cannot die one explicitly says "Other allies cannot die" to indicate it doesn't include itself.

Bringer of Fragility is indeed a 100% chance to apply Vulnerability on hit. The curse will be level 1. Similarly Bringer of Weakness applies Enfeeble, and Chronophage applies Temporal Chains.