Definitely buy the more powerful catalysts if u see them and don't already have them. IMO The best ones are hex and curse of knowledge ( both the generic version and character-specific ones). Strong character signature cata: Corrosive Element, Futile Resistance, Scratching Post, Sleeping Powder, Don't Poke the Buer, Return to Sender, Electrostatic Field. Powerful Elemental cata: Frost Armor, Into Thin Air, Last Words