Are you sad that Johnny has this great permanent out and you don't
Without it, your opponent could chump block your massive attacker with a 1/1 token to prevent the trigger
Play it late after your board is filled with dragons and a haste anthem of some kind, or play it early and use a Warstorm Surge to burn your opponents with your dragons fire
And doubling energy production each time is just a massive value, even if you arent using it to more easily go infinite
Its third chapter and last ability is a board wipe (yes, in blue!), which destroys all creatures and replaces them with 2/2 Phyrexians
Because all of the Meteorites and Treasure tokens you make will double their generated mana, Roxanne is perfect for quickly playing massive creatures like Ulamog, the Ceaseless Hunger or Etali, Primal Conqueror