From what my Search attempts have told me, this trick had not yet been posted. I'm shocked.
Step 1) Be a high level Egoist. Also being a Thrallherd makes this easier.
Step 2) Manifest Fusion on a friendly cleric who can cast Miracle (or at least use a scroll of it).
Step 3) While in your fused being state, use Miracle to cast Simulacrum. Miracle so you don't have to worry about the long casting time. You now have a lower level clone of your fused state who, from what I can tell, is its own being and thus permenantly fused together.
Step 4) Fusion ends. Manifest fusion with your lower level fused clone.
Step 5) Miracle Simulacrum (the clone has cleric casting, it can do it now on its own).
Step 6) Repeat forever. Each time you fuse you gain the clones hp and power points added to your own, so each time you make a clone it gets stronger and stronger and stronger.
Does it work? It looks like you can grab NI Hp and PP this way. And if the clone can manifest fusion somehow, it could start adding other classes to its superpowered state, clone itself, and repeat. It's HD would be reduced each time but fusing with its higher-level self increases its effective HD again so it never drops lower than 1/2 your level.
