Good trap cards are those that can: prevent attacks like Mirror Force, negate summons like Solemn Warning, negate spell/trap activations like Wiretap, negate effects like Breakthrough Skill or Fiendish Chain, remove monsters like Ring of Destruction or Compulsory Evacuation Device, and prevent your opponent from making plays like Vanity's Emptiness
While you can find plenty of good options if you run Delney in the command zone, there are even more to choose from if you add other colors
Its basically a mono-red with three (or sometimes even four) splashes
Deck looks super sweet, rumble being able to dig for both halves of the combo (bc twin is a perm) is awesome
Bandit Citadel Plane: Kamigawa Whenever a creature attacks, it gets +2/+0 until end of turn
This is stated in the spells text