Just need to boot up DuelingBook and put the most generic search criteria you can think of. Like, if you're looking for a Battle Trap, just hit up "Trap" and search for desc "Attack" and see what's the coolest for your deck. Maybe you'll find a card that combos with some of your others? Like, I looked for something that'd work well with Vennu, Bright Bird of Divinity by typing "Tribute" into the "desc" bar and see what I could find. You might just find the coolest combo ever, that you can keep in mind until a very important duel comes up.