revamp Plasma Field upgrade

[DreadKnight]

The upgrade for Dark Priest's Plasma Field could change the whole ability to only shield attacks if they're deadly blows. As a result, this would make first rounds of a match usually a hit rush until the ability upgrades, speeding things up. On the down side, freezing/stunning abilities could be very OP.

[DreadKnight]

Or have the shield block ability effects or to only trigger when bellow a health (fixed or %) threshold, but this would make a rather low health priest that has a lot of plasma prone to die from a high damage hit.