Metal Pokmon are strong against : Water and Psychic Pokmon
Pressure and counterspells good against combo
On PTCGO, it is possible to build a huge collection from nothing with the trading system, however it is widely considered to not be intuitive or beginner friendly
Return to Ravnica was also notable for producing one of the most absurd Limited cards in Pack Rat, but its the Shaman that defined Return to Ravnica for me: intriguing on the page, domineering on the table
You can check out the cards that are included below
There are a bunch of Commander Classics like Hornet Queen, Nantuko Vigilante, Caustic Caterpillar, future strong cards like Haywire Mite, multiplayer classics like flying regenerator Fog of Gnats and the card drawing and recurring Grave-Shell Scarab, token making Ant Queen, game winning rampers like Moldgraf Monstrosity, Giant Adephage and Living Hive