Since it can't hurt for me to tell you now, feat does-
When it targets an ally next to DM, it reverses that character's HP. Like, if they had 2/10 HP they now have 8/10, and if they had 11/20 they now have 9/20.
When it targets an ally far from DM, it doubles that character's defense until DM's next turn.
When it targets an enemy next to DM, it stuns that character, like Push or Hypnosis do.
When it targets an enemy far from DM, it halves that character's defense like disbalance did.
When it targets DM, it gives him the power to temporarily attack by only using 1 move point. You saw this one. It can be powerful.
When it targets a dead ally, DM kills himself to bring that ally back to life. That ally gets the amount of HP DM had before he died. I kept telling Radium, during the testing, that summoning DM near the players was stupid and it would be smarter to let him hang behind and lower the enemy's defense and bring Lance or Talon back when they died. Apparently he never listened.
When it targets an empty square, DM jumps to there. He doesn't use any movement points in the process.

So, as you see, the only thing feat doesn't affect are dead enemies. This skill even ignores magic immunity.