It's definitely an interesting and cool new interaction introduced to change Poxnora's gameplay a little. Additionally, it was an interaction that was added to every respective faction, each being pretty overpowered...so technically...it's balanced.
It's essentially the same mechanic as psychic agony, nothing really new and all of the invoke abilities are indeed broken especially that sp one what a laugh.
They had to give it a large aoe that way people actually bought them, with an aoe 2 people would just attack from range and not even give the ability a second thought similar to psychic agony. I personally don't like any ability that relies on my champion getting to half health for it to fulfill it's purpose.
Except you know psychic agony is a thing, so it's not really a new interaction. I prefer no new abilities though and instead runes that are properly balanced and have a role to play in their selected theme.
The new invoke abilities can be used even before a champion's HP is below 50%, or at least for the Elder Vampyre that is the case. Haven't bothered with any of the other champions since I only play Vampyres. I did notice in a match I popped the ability off manually (the champion never fell below 50% prior) and then it went off a second time on my opponents turn when they dropped it below half HP. Seems reasonable to me if every faction has a champion capable of that. However, this isn't something I want to see on 5-6 champions. It'd become broken in a FW suicide deck for sure.
