How about an End themed power source, utilizing the forces and resources of the end to make a new powersource which is nearly limitless but extremely dificult to make.
for an example.
An Ender Core.
P=enderpearl
E=energy crystal.
Dr=Enderdragon Egg.
A=advanced circut
PEP
ADrA
PEP
this would be the power sources fuel essentially, but it would be extremely dificult to maintain, the core itself would be he same strength as an entire 6 chamber reactor and ten times as unstable. so without proper setup it would explode with the force of 10 nukes.
as for the setup, the core will be a three block high one block thick chamber which the Endercore will be in the center held by only 2 tubes top and bottom.
as for the containment and such, there will be 4 focused lasers, all equally distanced in diameter and radius from the core and each other.
the lasers each focus into a large 12 block ring around the core which in turn creates a force field and energy tap. the force field will deploy up 25 blocks and down 25 blocks, it essentially is just as so
D D D D
D..... D
D..... D
D D D D
The D's are just the closes thing to a block at the time without confusion.
the bottom and top of the core are the only things you can use to tap into the power source.
this new power source would require an enormous amount of work and planning to maintain.
the entire setup is similar to a nuclear reactor in terms of GUI.
the following are what are needed to keep an Endercore running without problems. Whereas a nuclear reactor needs to quell heat, the Endercore needs to contain power.
in that sense a Capacitor is needed, consisting of 3 ender pearls, 3 laptron crystals and 3 glass fiber cables. the ender pearls in a V formation, Laptron Crystals in an upside down V and the cables filling in the rest.
there is also a need for a power regulator which requires 3 redstone timers. an MSFU, and 4 Advanced Circuts.
lastly there is a need for an internal forcefield to help contain the power. this is the most expensive and dificult device to make and you need 4 of them.
the recipe is basically this, you need 9 stacks of advanced alloys all in a block pattern filling each part in the recipe block. then you need to take the 64 (Titanium) blocks then put 16 in each corner of the recipe table. then place a Laptron Crystal in the dead center. and fill the bottom top and left plots with fully charged mining lasers. and the left plot a glass fiber cable.
these need to be 3 plots away from the center where the powersource is.
there is a lot more I wanna add, but I have to think it through more, a lot more.
I do know one thing that I would love to see, there would be an option to make an Emergency vent device which channels the surge of energy into a directed purple laser about 4 blocks thick and will attract a lot of endermen.
just to reiterate these are not multiblock machines...aside from the ring of D's which has no multiblock GUI but instead just there acting like connected redstone, and the main reactor chamber ( many times reffered as the endcore) will be just a visual aspect and works like the ring of D's regardless if you have 1 or 2 the GUI stays the same.
You're probably going to turn around and say "OMG see ic2 has magic!" but IMO its more Star Trek(/sci-fi)-ish where as your suggestion is probably what I'd call 'Harry Potter'-ish.