Gagaga Gardna

The effect "When an opponent's monster declares a direct attack, you can Special Summon this card from your hand" is a Trigger Effect that activates in the hand. (It does not target.)

The effect "When this card is selected as an attack target, you can discard 1 card; this card is not destroyed by that battle" is a Trigger Effect. (It does not target. You discard 1 card as a cost to activate this effect.)

If "Gagaga Gardna" is selected as an attack target when an opponent's monster declares an attack, or if "Gagaga Gardna" is selected as an attack target due to a replay, you can activate the "this card is not destroyed by that battle" effect in either case.

The "this card is not destroyed by that battle" effect can be activated each time an opponent's monster selects "Gagaga Gardna" as an attack target. (If multiple opponent's monsters attack "Gagaga Gardna," you can consequently activate the effect multiple times in one turn.)