You'll never be able to convince me that Mind Spike is worth it. The Battlemind is one of my favorite classes and is my favorite defender (by a long shot). So when I play a defender, I often default to the Battlemind.

I've played it a lot. And out of months of play, I can count on one hand the number of times I've used it. Compared to the small amount of a Fighter I've played where Combat Challenge gets activated ... a lot. It's clear that one feature is far stronger than the other.

I'm often stingy with my power points, too.

I know that I'm arguing personal experience, but everyone else has already argued mechanics. Mind Spike is pretty pathetic. Not just because it so very rarely triggers, but because it also doesn't do much damage. Even in the most optimal situation: the enemy crits on an ally for 100 damage. Great, you've just hit the enemy for 100 damage. It's likely to survive that. Your ally? He's probably on the ground begging for a heal. Enemies have more health, so hitting them back for the same amount they do you? It doesn't hurt them.

Compare this to Lightning Rush, which can easily trigger far more than 100 damage, and all of it as an interrupt so it will likely kill the monster before its 100 damage gets applied.