Which Dilettante power for a battlemind?

[Yakk]

This is why your DM's roleplaying approach is part of how your defender works

If anything, the DM's "roleplaying approach" is nerfing how your defender works.

Unless parties with a lightning-trip-switch like the PCs are well known or common, the immobilized monsters suddenly taking total defence because unrelated creatures elsewhere in the world ran into a trap seems pretty questionable.