I have to concur with what other have said on the list.
I made a new blaster and Defiance seems to work well at lower levels. At higher levels it seems worthless. I tried to get hurt with my level 50 blaster to see how the power would work out, but that just lead to a quick death. When I get down to 40% health, just one or two hits will send me to the hospital. I also tried this with a team, but I either stayed at full health or died too fast for the healer to save me when it got to the point that defiance would kicked in.