a d10 (nWoD-esque) powers with consequence

[JeenLeen]

I like the idea of certain powers having drawbacks. However, often when I see these in systems or try to create them, it winds up as "the drawback is inconsequential so it might as well not exist" or "the detriment is so bad that using the power is essentially a non-option". There's no real feeling of temptation or risk. I was pondering some about this, and about Warhammer 40k's psionics/Chaos magic, and it gave me an idea. In point-buy systems, this means that the powers-with-detriments are usually poor choices to buy, screwing you over one way or another.

This is based in a homebrew using roughly nWoD's d10, with simplification in skills and attributes, but you can probably ignore that for these purposes.

The idea is that some powers are open to everyone in the setting (or at least all PCs) at no character-creation/xp cost. Other powers cost xp. The free powers are the equivalent of Fortitude, Celerity, Potence, a healing power, and a few other themeatic things. Maybe a 'war form' where you shapeshift using the powers of chaos you have invoked. Except for Fortitude/Celerity/Potence, some equivalent power will exist among those you can pay xp for.

Essentially, every time you use a free power a dice pool (called the Warp pool) increases by 1. If you use a free power, you roll Warp against your Will (rated 1-5) and, if your Will gets fewer successes, you suffer something like a Paradox backlash from oWoD mage. If you backlash, you may but aren't required to decrease your Warp by the size of the backlash. If your Warp pool gets high enough (maybe 5), you start to risk backlash even using non-free powers.
Some free powers are more effective with a higher Warp pool, essentially your Warp pool being your dice pool for those powers.
I see the pros of this as

setting-wise, makes everyone dangerous as it is known they have lethal powers they can invoke if they don't care about Warp contamination (like cultists)
players can choose to benefit from powers-with-consequences, BUT
they don't pay an opportunity-cost to get the powers

I may make a 'safe power' being something like Warp Resistance, giving you a bonus to your Will roll or decreasing backlashes slightly. Basically let the player spend xp to be able to more safely use the free powers, BUT try to balance it so that Warp Resistance isn't basically a tax everyone has to pay to be effective.
And I plan to have it be feasible that someone never use the free powers, but I reckon there'll be times when, backed against a wall, getting an easy boost to finish off a foe or a quick healing would be used--basically, it gives a feeling of temptation that has some reality to the player.

I realize this is bare bones, but does this sound interesting?

[lightningcat]

I completely misread this idea the first 2 times I looked at it. I was thinking you wanted a single Warp Pool for the players. Having something like a Doom pool for a rpg sounds like it could be fun. I think some other game has done something like it, but I could not tell you which one.

A few things about your actual idea.
First, I think you should have other abilities that also increase the Warp pool. Either higher level abilities or an entire path (sorcery or the like) that does so. That way Warp Resistance is more then a tax on the basic abilities, and gives your cultist more powers to play with. As well as those player that want to play with fire. There may even be powers that can only work if the Warp Pool is large enough.
Second, how fast does the Warp Pool reduce if powers are not being reduced? This will change how dangerous it is to use the powers. If it is reset every scene, this makes it easy to use them a few times each scene without worry. However it only is reduced at the start of a new story, then it is very dangerous to use them any more than needed.