The only way i can seem making cast when damage taken useful for me is to level it and link immortal call to it, while leaving all the other gems on manual. I don't think the nerf affects my build terribly, at least in principle. I have a 14 second duration on my endurance charges, so if i play it right i don't need to spam enduring cry at the beginning of every fight (plus i have the endurance charge gem linked to heavy strike). Casting Molten Shell manually is a bit of a problem since it forces me to stop hitting on enemies in the middle of a fight which is a death sentence for me since i rely on leech for survival, but i guess i can just leap slam out of a fight, pop the shield and get back in. Lastly, totems have to be cast before engaging in combat, which works for some but not for others (the vitality totem for instances has too little a radius of effect).
In principle. What makes this less then viable in fact is that i have no mana to do all that, not at the cost of sacrificing auras, which means i might as well spec back into blood magic.
So, again, there are several problems with this gem. One, the change they made forces you to play around gem levels to find an optimal spot, which is not a game i want to play, since changing the level of a gem costs either currency or time. For me, a gem ought to get better as you level up, otherwise its just bad design. Two, you cannot have a game with skills changing this radically every patch. It may have been fine on beta, but not on release, particularly in a game which offers limited respecting capabilities and where every "build" requires a great deal of investment in terms of time and currency.
I don't know about the other trigger gems since there are no "spell" linked to my main attacks, so there's nothing to trigger. Also, cast on death, does this actually drop in hard core?