Whenever one of my monsters is bloodied, I allow my players to make intimidation or diplomacy checks against it as a minor action. If the party scores a certain number of successes (8 for a solo, 5 for an elite, 3 for a normal enemy, or 1 for a minion) the monster may be convinced to surrender.
The monsters don't get any such advantage against the player characters.
One problem with all these "penalties when bloodied" ideas is that they significantly nerf builds that require you to be bloodied to get certain bonuses, because then you ahve to accept the penalty to get the bonuses. (But as long as players know about this, they can simply avoid such builds.)
Whenever one of my monsters is bloodied, I allow my players to make intimidation or diplomacy checks against it as a minor action. If the party scores a certain number of successes (8 for a solo, 5 for an elite, 3 for a normal enemy, or 1 for a minion) the monster may be convinced to surrender.
except as a way to nerf encounters that are taking too long