There has been questioning, and now answers! Energy Drain is something that you can normally only do to a person within arms' reach of you. It generally requires close contact, but not skin contact, and is extremely obvious. People (and for those who can use a similar effect on terrain, things) affected by Energy Drain are visibly tired and worn out. A tree starts to droop, flowers wilt, etc. You can stop this effect by barely taking any energy, but what fun is that?