Acually, natural fusion would be a good way to produce extreme heat, which could be very useful, and there's no fallout or anything.
How on Planet will we find a use for that much heat? Especially since we would need to generate a lot of heat to make the fusion start, plus a lot of hydrogen.
For one, it would give us a few thousand firejackets. It could also be useful for creating some sort of white hot fire elemental. And perhaps we could use the heat to generate mana somehow?
1. Surely there's less destructive methods to get firejackets?
2. AKA a Collateral Damage Elemental if we use it near anything flammable.
3. Maybe, but again, there has to be a less destructive and more efficient way to do so.
4. Where would we get all that hydrogen?
1. But less effective. And less !!FUN!!
2. Things on fire work better than things not on fire- Guild of Pyromaniacs
3. Not neccesarily, we would have to see.
4. It is literally everywhere. Hydrogen is a part of MH4, H20, and many other compounds, as well as being found in the atmosphere in small amounts.
1. Effective? Sure. Efficient? Likely not, compared to (say) sending them into fireplaces or something. Safe? Heck no.
2. No, they don't. They just can't be used as long and set stuff on fire.
3. Since it would be white-hot...that sure sounds like something that would cause collateral damage.
4. How easy would it be to...god, right.
And also in stars, which I'm sure we, as a god, could reach.
We could power our mana on the suns' natural fusion if we could get some sort of generator up there...
And so begins the DSP
We should just toss some firejackets into a sun. 
Vacuum's probably not healthy for them...
Assuming a speed of 20/mph, it would take the firejackets 1061 years round trip.
Assuming the sun is the same distance. But we could get them going faster than that.
A hundred miles an hour will get them back in a fifth of that time - something like 200 years.
two hundred miles, 100.
Four, 50.
Eight hundred and it's a measly 25 years.
Now, light speed - we can get them there and back in twenty seconds. Assuming that the atmosphere doesn't tear them up.
I'd like to question these numbers. Assuming a distance about equal to one AU, it would take a bit over 16 minutes, round-trip, to send firejackets to Sol.