Mist Valley Thunder Lord (Duel Terminal) (Duel Terminal Technology Common) - Hidden Arsenal: Chapter 1 1st Edition

1 Tuner + 1 or more non-Tuner "Mist Valley" monsters

Once per turn, you can select 1 card you control. Return it to the hand, and this card gains 500 ATK until the End Phase. This effect can be activated during either player's turn.