Proof? I certainly can't see Crono and co. seriously becoming that powerful in a matter of a few days of time travel. The only real power that they gained was magic, and in my theory, it wasn't even the true power of magic, just a part that was made up of true Shadow Magic.
There is simply no explanation to why they're that strong except for that the entity did it or that truely, all that spirit energy helped them. If the Planet gave them that power, it would certainly weaken it after Lavos is dead. Any spare power, it would need. And what if for instance, Crono found the rogue Masamune? Then what would have happened. His "powers" plus the sword = Death to all...
And then Lucca was kidnaped by Harle and Lynx. If she is able to withstand a destruction from the heavens and acctually hurt Lavos, but can't stand up to Harle or Lynx, then she has serious problems.
If she can penetrate Lavos with a punch, or a gun pretty much, she could wipe Harle and Lynx baaad. Or use magic, or a tech like hypnosis or flame bomb or something... but no...
And magical elements (Water/Fire etc.) are controlled. Did Lucca's fire spell ever set the carpets in the Throne Room in Zeal on fire? Noo..... Did it burn down other places? Noo... I'm thinking that only physical fire is uncontrolable, but magical elements are... So
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And yeah, I don't like Kat from BoF2. I LOVE NINA!