Quote Originally Posted by Klorox View Post
I thought you didn't gain HP in a dual class until the new class passes the old classes level.

Please explain.
No, you still gain HP. You can't use the abilities of your old class again until your new class has passed the level of the old one. Well, you can use the old class abilities, but if you do you don't get any XP for that adventure. The only thing you have from your old class is the HP and the saving throws, until you've gained enough levels.