There are a number of things I question in 4e and some things I like. But most of the time, I "get" why things were done in a certain way even when I disagree.

One thing I don't understand right now is power sources. Each class has powers that come from an energy type. The PHB describes three sources: Martial, Arcane and Divine.

And we're told that future books will describe more sources. Those mentioned are:

Elemental
Ki
Primal
Shadow
Psionic

Wow, that's a crapload of power sources. That sounds like fun... except I don't get much differenciation between the different different power sources already revealed.

Are there going to be in-game ramifications to power sources? What sort of cool things could this lead to, if any? Low mana/high mana zones like GURPS, where arcane powers would be affected?

Or are these "power sources" mostly a meta-game tag like "controller", "defender" and all that?

Because right now, it seems the source identification doesn't change much, if anything. Most powers for the eight classes are similar enough that I fail to see how the energy type matters.

First, energy type is something else (and interacts with various weaknesses and resistances with monsters). Second, I have a feeling it's setup for later clarification in the supplement line. I vaguely remember (for example) Faerun having areas tied to shadow and what have you. Or things like arcane magic defiling the landscape in Dark Sun. So yeah, high and low magic areas for different sources, various kinds of "antimagic" etc. may all be possible.

I think in the core rules, though, it's just fluff.

Yeah, it's currently an underutilised metagame mechanic that begs for more uses to be found for it.

As a possible house rule, you could set up certain places and times that are particularly potent for an energy source. Anyone who draws on the correct power source while in it is able to use one of their powers (utility, encounter or daily, depending on the potency of the site) twice without needing to wait. A coliseum with a large crowd chanting for the blood of gladiators, for example, might spur on those who draw from the martial power source. A conjunction of the moons might work for arcane users, while a temple dedicated to the correct god does so for any divine user who is devoted to the god.

I'm wondering when 4e will get it's own sub-forum.

The only mechanical reference to power source I've come across is with wands, where you can only use a wand which utilises abilities from your power source. So a wizard can use a wand containing a warlock power and vice versa, but a cleric cannot.

Quote from: TrevelyanThe only mechanical reference to power source I've come across is with wands, where you can only use a wand which utilises abilities from your power source. So a wizard can use a wand containing a warlock power and vice versa, but a cleric cannot.

Which I guess makes the power sources pretty much the same as they've always been in DnD, but simply with more added. Makes sense to me I guess. Personally, I wouldn't differentiate between Martial and Chi, but otherwise it seems reasonable to me.