Arlough, the online Compendium is incomplete in the rules text of the Immune entry from both the PHB3 and Rules Compendium.
I thought the whole point of the compendium was it is supposed to have the most up to date rules and rule text.
Also, I had forgotten the clarification in PHB3. Thanks for pointing that out.
Immunity to one part of a power does not make a creature immune to other parts of the power. For example, when a creature that is immune to thunder is hit by a power that deals both thunder damage and pushes the target, the creature takes no damage, but the power can still push it.
So, if you are immune to one damage type and you get hit by a power that has two damage types, you are not immune to any of the damage. If a creature is hit with a power that deals 20 Cold/Necrotic damage and it has Immune Cold and Resist Necrotic 5, it will take 15 damage, because it is not immune to all parts of the power and has to use its lowest resistance against the power (since immunity is really just a level of resistance).
I believe in the very last sentence the rule above actually states specifically that, in the case of a power of multiple types, one of which you have an immunity to, you will not deal any damage, but you will be able to execute effects of that attack. So in the example of the power that deals 20 Necrotic/Cold and the creature has
Immune Cold and
Resist Necrotic 5, it will take no damage at all.
Additionally, since Poison is both a damage keyword and an effect keyword [PHB1.055 - keywords], poison immunity would also eliminate any effects of the attack.
I don't like the idea that a multi-element attack, given how hard they are to come by anyway, would still deal no damage. And, I don't like one immunity stopping all damages and effects from an attack, especially the most common immunity.
So I do think that I am going to stick with a new damage keyword to replace poison damage with, as well as replacing all damage immunities with
Resist All so the resistance stacking rules apply instead.
But thank you very much for finding that reference for me. I was so busy looking for the rules clarification to be in the rules updates that didn't even look in PHB2 or PHB3.
