Chronopolis (Phase Metastasis)
In Chronopolis, an experiment on Phase Metastasis is said to be underway (by a Chronopolis ghost stuck in a time prior to the Time Crash). The actual process is a mystery, and has proved a point of inquiry for fans.
Record of FATE Transmission
Metastatis means, "transmission of pathogenic microorganisms or cancerous cells from an original site to one or more sites elsewhere in the body, usually by way of the blood vessels or lymphatics." Taken in a different light, it could mean the introduction of new neurotransmitters to the brain by Records of FATE as they overwrite personality and memory to control the citizens of El Nido biologically.
Just going from the roots, and a scientific point of reference, it would most likely refer to keeping something in a constant, unchanging state of matter, such as keeping a material in a plasma form, or some such thing. Quite possibly, he is refering to either a) some key component of FATE, B) FATE itself, or c) something unrelated and pertaining to their understanding of time travel. It's entirely possible that Lucca's Gate Key has something to do with the afforementioned Phase Metastasis. It could be that it operates by forcing the Gate into a single state, or "phase," and holds it in stasis there, possibly through some electromagnetic field, therby allowing travel through it. As for the FATE possibilities, it could be that FATE is a plasma creature, like the Dragon Gods were, and that the entire computer only works because it is in "phase metastasis."
The Enlightened Ones originally wanted to use Lavos power to achieve immortality. Perhaps phase metastasis refers to a way of halting aging, perhaps like the same effect Queen Zeal achieved when she allied with Lavos after the Ocean Palace Incident. It could put the aging process or body in "stasis", and it would thus never age.
From: Theory (Locations)