Update:
A kind soul e-mailed me the answer to this one:

612.3. Effects that add or remove abilities don’t change the text of the objects they affect, so any abilities that are granted to an object can’t be modified by text-changing effects that affect that object.

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Player A has a Dark Impostor which has exiled a Galecaster. Player B plays New Blood on Dark Impostor and gains control of if. Can player B tap vampires to bounce nonland permanents?

In short, what does “all text” include? Does it include copy effects?

Edited Olle Liljefeldt (Oct. 1, 2017 10:33:41 AM)