[Endoperez]

The hitpoints bonus of battle comes from the last turn's bonus. That is, if your pretender moved to the province where the battle took place from a province which had high dominion the turn before, he would have had the hitpoint bonus from the dominion of that province. His dominion bonus of this turn is used in the next turn's battle, even if he teleports to a province with negative dominion.

My explanation is somewhat confusing, but I hope it helps.