The change to Floodborn is unpredictable, but the seeds are already present in the Storyborn or Dreamborn glimmer. Rise of the Floodborn will be released in local game stores on November 17 and mass market retailer stores on December 1.
The card is sitting at $255, marginally more than Hades, but it does seem to be dropping slightly
Unless that signatures from a big-time Magic name or artist, its unlikely that getting your cards signed will have a positive effect on the grading or value of that card
Rofellos, Llanowar Emissary The history of Rofellos is long and winding, being banned, unbanned, and then re-banned, but its major significance comes from its role in the creation of the commander tax
Finality counters keep the card from being too recursive or broken, and its expensive to get into play, but the effect is worth having around in typal decks that focus on larger creatures, like giants or angels
Idol of Oblivion I'd normally say Idol of Oblivion should be reserved for token decks, but so many decks can produce incidental tokens these days, so the Idol probably has more homes than it might seem