If you're using tantra (vajrayana) for ego-oriented material benefit, then that's called "spiritual materialism." According to Tibetan Buddhism, the vajrayana can be dangerous for you and those around you.
Edit: I apologize. I realize that was very heavy handed. I felt obligated to throw out the usual warnings about Buddhist tantra.
No worries! I'm familiar with Trungpa's warnings about spiritual materialism. I know the context of Vajrayana is quite different from the "Batman Effect" discussed in the original article, but I wanted to spur discussion in general about the power of assuming the identity (transitory though it may be) of a chosen figure.
And for anyone who's interested in tantra, I'll spell out the warnings more explicitly: this kind of practice should only be attempted under the careful guidance of an expert - a teacher who is empowered by a qualified lineage. These kinds of visualizations are very powerful, and can be dangerous to one's mental health if done foolishly. Hacking with the boundaries of one's ego and merging with deities is not to be done lightly. Seek expert instruction.
Consider the neurological danger of visualizing yourself as (e.g. hitler) repeatedly over and over. The exercise mentioned above is one of neurological conditioning (anpassen in german). You are training your neural pathways to take on a certain form of thought pattern. If you pick (e.g.) hitler as your mould, then you are training yourself as hitler. That's what the danger is with such a practice.
Therefore, you must be careful and wise about what neurological mould you are seeking to "impersonate" with your practice, since you would be creating new habits and neural pathways in practice.
I'm not an expert on this topic, but I can use my common sense to figure that out.
> Is that because this whole stuff is incredibly in fashion in SV?
Well, I grew in the rural South and currently live in Wisconsin, so I don't think I'm succumbing to some kind of SV hippie group-think.
The literature and instruction of Vajrayana is filled with warnings about using the techniques improperly. And they are very powerful, with tantra having developed during the peak of sophistication of Indian Buddhism in the 6th-9th centuries. The Tibetans have refined things further. E.g. the emergence of Dzogchen and Mahamudra.
Re: Hitler: Playing with the boundaries of self-identity as a form of daydreaming for the average person probably isn't harmful. But tantra combines a number of introspective technologies that hugely amplify the depth of concentration and effects of the exercise on the entire body-mind.
Weaving together ritualized breathing practices, somatic visualizations (i.e. energy work), external auditory stimulus (bells, etc.), chanting, internal/external visual aids (mandala), in the social context of serious vows to one's teacher, the Buddha, and all other sentient beings in the universe. . . well, it turns everything up to 11, so to speak.
Submerging oneself in an imaginal identity as a deity under those circumstances can provide a sudden, inarguable new insight into the boundaries and nature of one's self-construct, so the so-called truth of anatta. It can reveal in a flash the moment-to-moment fabrication of a particular kind of self-narrative you've been engaging in your entire life. And you can experience the incomparable freedom of being freed from that straitjacket.
Or if you're winging it without proper instruction, a similar exercise can deeply fuck you up, leading to weird somatic illnesses, grandiose thoughts (you think you _are_ the deity, or Hitler, or whatever), manic states because you don't understand how to safely bring down your psychological arousal level, etc.
Edit: I apologize. I realize that was very heavy handed. I felt obligated to throw out the usual warnings about Buddhist tantra.