Anakin, dressed similar to the Vader we know and love (not yet a cyborg) has attained the force focussing Kyber crystal at the Emperor's behest and places it in an acnient shrine on Mount Naboo. Then he begins concentrating his energy and slots his palms into the shrine's long dormant device.
He aims to become the most powerful Jedi ever but his Dark Side energies corrupt the light force power and rejected shoot down into the planet's core causing terrible planet-wide earthquakes.
A quick shot of Ootah Gungah revelas it to have been instantly vaporised by jets of lava racing to the surface.
The ground around him cracks open with eruptions of steam and fire.
Obi Wan shows up to stop him but is too late and as the planet destroys itself around them the two old friends begin their climactic showdown.