Great Card: Armored Kappa

If you are playing Mermails, Agents, or Atlanteans this is a great card. If you XYZ summon him with Atlantean Heavy Infantry and you detach him you get Infantry's effect. By discarding a card you can protect all your monsters from harm and if you discard an atlantean you get there effects.

(Credit) here is his effect: Once per turn: You can detach 1
 Xyz Material from this card; this card gains 1000 ATK or DEF.
 During either player’s Battle Step, while an attack involving your
 monster is occurring: You can discard 1 card; for the rest of this turn,
 monsters you control cannot be destroyed by battle, also
you take no battle damage. You can only use this effect of “Armored Kappa” once per Duel.