Raid Rules:R101.3a Bosses can be destroyed only by fatal damage. Opposing modifiers can’t turn a Boss over or remove its powers (unless that Boss is the source of the modifier that does so).
As quoted from the official Raid Rules document, opposing modifiers cannot remove the powers of a Boss. So Dragon's Breath could be used to deal damage to a Boss, but would do nothing to remove its powers.
Magneto:We are the future, Charles; not them.
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