Quartz
Hero
Why not simply cut to the chase? Before the final session, tell the players to add 10 (or 15 or ...) levels to their characters then immediately launch into the final battle? "You finally confront XXX in his lair: all his clones are destroyed, he cannot retreat. He looks at you with a sneer: 'Destroy them, my minions!' Roll initiative."
You might do an intermediate session with +5 levels.
You might do an intermediate session with +5 levels.
