Answer for Q1: It always depends according to your preference, even if it's just a general non-restrictive faction deck. There's that deck that focus mainly on buffs, others debuffs, or can be a mixture of both. For budget build deck, there's always the "Passcode Deck" where every followers in your field with same size buffs a lot at same time. There's also this "Normal Deck" featuring some mixture of both buffing and debuffing like Disappearance spell, etc. There's also the "Pure Debuff Deck" where everything is focused in burning enemy HP and/or destroying enemy followers in a single move. There's also (aside from those 3 aforementioned decks) the special type decks where focused on something else (locking enemy field, stalling, etc.). So in the end, it depends on your build, if you want your deck to be the "best". As for low budget deck, I will suggest Passcode Deck. Answer for Q2: Pretty much dead for NA/INT servers, since this is already locked on KR. Dunno if this game is still available on JP server.