When creating your character, please keep in mind that you can take up to three background as well. Backgrounds are bonuses that are conferred based on your past.
There are some good generic backgrounds, as well as guidelines for choosing backgrounds, in the
Player's Handbook 2 and there are a huge amount in
Dragon Magazine #366. You can find specific power source backgrounds in their respective power books, IE Primal Power and Martial Power 2 but not Martial Power 1. There are some more powerful backgrounds in the
Forgotten Realms Player's Guide, but those will be tweaked by me before I will approve them. Please take a look at these and feel free to choose any one you like. Don't worry about the descriptions as the main focus is the benefit. If you want to rename the background then go ahead but let me know what the original name is so I can look it up.
If you want to create your own background, please look at the books above before deciding what you want. There is a large range of benefits, from bonuses to skills, to getting an extra death saving throw. If you still can't find the exact match of bonuses you want, then let me know and I will look at your backstory and take your request into account to create a background benefit for you. Try to keep requests reasonable, please.
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An example of a bonus from your backgrounds would be: A +2 bonus to Arcana checks and it takes four failed death saving throws to kill you.
There are other benefits but I prefer you to stick with that format. A bonus to a skill and an alternative bonus. You can substitute the skill bonus for adding that skill to your class skills list and, if you'd rather have
just skill bonuses then you can choose two skills associated with your backgrounds and get a +3 bonus to each.
I know this is confusing, especially since we've never done this before, but if you have any questions then PM me and I'll try to help as much as possible.