Ah, Lavos...
Chrono Trigger was, is, and shall remain to be my favorite game (the adjective 'video' is optional) of all time. This favoritism extends to its soundtrack, as well. You've done a great job with the song. I like it. :D
P.S. For the record, both Lavos and Zeromus are easy. Lavos simply requires Lucca's and Robo's last Double Tech a few times (Double V Bomb or something, I can't remember), and Zeromus, as huge and evil as he is, is susceptible to the Toad spell. Yes, you can turn the big hulking mass of pure Lunarian hatred into a toad. Or at least, you could in FFIV Advance. Not completely sure if it stuck to the other versions.