[WarxePB]

As for your question:

Keeping the pods' HP equal to the heroes: Yes, you'll have to have an event in every monster group that checks the HP of the hero every turn (Turns Elapsed: 1x), that removes the pods' HP (Remove Hero HP for both pods, make sure to uncheck "Reduction can Kill Target"), gets the hero's HP (Variable Operation) and sets the pods' HP to that (Add Hero HP, with the Variable function using the variable from above). That seems like the easiest method.

Making the pods invincible: In the Heroes tab, give them E resistance to everything. This means, however, that every enemy attack would need to have an attribute, so you won't be able to use any of the Basic actions for monsters.

Pods die when hero dies: In the check HP event, add a Conditional Branch at the end that checks if the variable you used for the HP check is 0. If it is, simply add the Death conditions to both pods.